The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment that specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

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The information in this prospectus is not complete and may be changed. Neither we nor the selling stockholders may sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, and neither we nor the selling stockholders are soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to completion, dated February 24, 2012

Prospectus

            shares

Common stock

This is an initial public offering of shares of common stock of Vocera Communications, Inc. We are selling              shares of common stock, and the selling stockholders are selling              shares of common stock. The estimated initial public offering price is between $             and $            per share.

We have applied for the listing of our common stock on the New York Stock Exchange under the symbol “VCRA.”

We have granted the underwriters an option for a period of 30 days to purchase up to          additional shares of common stock. We will not receive any proceeds from the sale of shares by the selling stockholders.

Investing in our common stock involves a high degree of risk. See “ Risk factors ” beginning on page 13.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed on the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

                    , 2012

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VOCera

Communication solutions for healthcare professionals

The Vocera Communication Platform

Caregiver

Patient

Vocera

Nurses

Doctors

Support Services

Vocera helps hospitals improve patient safety and experience, caregiver satisfaction, and hospital workflow efficiency and productivity.

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R isk factors

You should carefully consider the risks described below and all other information contained in this prospectus before making an investment decision. Our business, financial condition and results of operations could be materially and adversely affected if any of the following risks, or other risks and uncertainties that are not yet identified or that we currently think are immaterial, actually occur. In that event, the trading price of our shares may decline, and you may lose part or all of your investment.

Risks related to our business and industry

We have incurred significant losses since inception, and may incur losses in the future.

We have incurred significant losses since our inception and may incur losses in the future as we continue to grow our business. As of December 31, 2011, we had an accumulated deficit of $56.9 million. We expect our expenses to increase due to the hiring of additional personnel and the additional operational and reporting costs associated with being a public company. If we cannot achieve and maintain profitability, our business will be harmed and our stock price could decline.

Our ability to achieve and maintain profitability in the future depends upon continued demand for our communication solutions from existing and new customers. Further market adoption of our solutions, including increased penetration within our existing customers, depends upon our ability to improve patient safety and satisfaction and increase hospital efficiency and productivity. In addition, our profitability will be affected by, among other things, our ability to execute on our business strategy, the timing and size of orders, the pricing and costs of our solutions, and the extent to which we invest in sales and marketing, research and development and general and administrative resources.

We depend on sales of our Voice Communication solution in the healthcare market for substantially all of our revenue, and any decrease in its sales would harm our business.

To date, substantially all of our revenue has been derived from sales of our Voice Communication solution to the healthcare market and, in particular, hospitals. Any decrease in revenue from sales of our Voice Communication solution would harm our business. For 2010 and 2011, sales of our Voice Communication solution to the healthcare market accounted for 96.9% and 90.4% of our revenue, respectively. In addition, we obtained a significant portion of these sales from existing hospital customers. We only recently began offering our Messaging and Care Transition solutions, and we anticipate that sales of our Voice Communication solution will represent a significant portion of our revenue for the foreseeable future. While we are evaluating new solutions for non-healthcare markets, we may not be successful in applying our technology to these markets. In any event, we do not anticipate that sales of our Voice Communication solution in non-healthcare markets will represent a significant portion of our revenue for the foreseeable future.

Our success depends in part upon the deployment of our Voice Communication solution by new hospital customers, the expansion and upgrade of our solution at existing customers, and our ability to continue to provide on a timely basis cost-effective solutions that meet the requirements of our hospital customers. Our Voice Communication solution requires a substantial upfront investment by customers. Typically, our hospital customers initially deploy our solutions

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for specific users in specific departments before expanding our solution into other departments or for other users. The cost of the initial deployment depends on the number of users and departments involved, the size and age of the hospital and the condition of the existing wireless infrastructure, if any, within the hospital. During 2011, the initial purchase order for new hospital deployments of our Voice Communication solution ranged from approximately $50,000 to approximately $2.7 million, with an average initial deployment cost of approximately $360,000, which amounts do not include any additional investment in wireless infrastructure that may have been required in order to implement our solution.

Even if hospital personnel determine that our Voice Communication solution provides compelling benefits over their existing communications methods, their hospitals may not have, or may not be willing to spend, the resources necessary to install and maintain wireless infrastructure to initially deploy and support our solution or expand our solution to other departments or users. Hospitals are currently facing significant budget constraints, ever increasing demands from a growing number of patients, and impediments to obtaining reimbursements for their services. We believe hospitals are currently allocating funds for capital and infrastructure improvements to benefit from recently enacted electronic medical records incentives, which may impact their ability to purchase and deploy our solutions. We might not be able to sustain or increase our revenue from sales of our Voice Communication solution, or achieve the growth rates that we envision, if hospitals continue to face significant budgetary constraints and reduce their spending on communications systems.

Our sales cycle can be lengthy and unpredictable, which may cause our revenue and operating results to fluctuate significantly.

Our sales cycles can be lengthy and unpredictable. Our sales efforts involve educating our customers about the use and benefits of our solutions, including the technical capabilities of our solutions and the potential cost savings and productivity gains achievable by deploying them. Customers typically undertake a significant evaluation process, which frequently involves not only our solutions but also their existing communications methods and those of our competitors, and can result in a lengthy sales cycle of nine to 12 months or more. We spend substantial time, effort and money in our sales efforts without any assurance that our efforts will produce any sales. In addition, purchases of our solutions are frequently subject to budget constraints, multiple approvals, and unplanned administrative, processing and other delays. As a result, our revenue and operating results may vary significantly from quarter to quarter.

If we fail to increase market awareness of our brand and solutions, and expand our sales and marketing operations, our business could be harmed.

We intend to continue to add personnel and expend resources in sales and marketing as we focus on expanding awareness of our brand and solutions and capitalize on sales opportunities with new and existing customers. Our efforts to improve sales of our solutions will result in an increase in our sales and marketing expense and general and administrative expense, and these efforts may not be successful. Some newly hired sales and marketing personnel may subsequently be determined to be unproductive and have to be replaced, resulting in operational and sales delays and incremental costs. If we are unable to significantly increase the awareness of our brand and solutions or effectively manage the costs associated with these efforts, our business, financial condition and operating results could be harmed.

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If we fail to offer high-quality services and support for our Voice Communication solution, our ability to sell our solution will be harmed.

Our ability to sell our Voice Communication solution is dependent upon our professional services and technical support teams providing high-quality services and support. Our professional services team assists our customers with their wireless infrastructure assessment, clinical workflow design, communication solution configuration, training and project management during the pre-deployment and deployment stages. Once our solution is deployed within a customer’s facility, the customer typically depends on our technical support team to help resolve technical issues, assist in optimizing the use of our solution and facilitate adoption of new functionality. If we do not effectively assist our customers in deploying our solution, succeed in helping our customers quickly resolve technical and other post-deployment issues, or provide effective ongoing support services, our ability to expand the use of our solution with existing customers and to sell our solution to new customers will be harmed. If deployment of our solution is unsatisfactory, as has been the case with certain third-party deployments in the past, we may incur significant costs to attain and sustain customer satisfaction. As we rapidly hire new services and support personnel, we may inadvertently hire underperforming people who will have to be replaced, leading in some instances to slower growth, additional costs and poor customer relations. In addition, the failure of channel partners to provide high-quality services and support in markets outside the United States could also harm sales of our solution.

We depend on a number of sole source and limited source suppliers, and if we are unable to source our components from them, our business and operating results could be harmed.

We depend on sole and limited source suppliers for several hardware components of our Voice Communication solution, including our batteries and integrated circuits. We purchase inventory generally through individual purchase orders. Any of these suppliers could cease production of our components, experience capacity constraints, material shortages, work stoppages, financial difficulties, cost increases or other reductions or disruptions in output, cease operations or be acquired by, or enter into exclusive arrangements with, a competitor. These suppliers typically rely on purchase orders rather than long-term contracts with their suppliers, and as a result, even if available, the supplier may not be able to secure sufficient materials at reasonable prices or of acceptable quality to build our components in a timely manner. Any of these circumstances could cause interruptions or delays in the delivery of our solutions to our customers, and this may force us to seek components from alternative sources, which may not have the required specifications, or be available in time to meet demand or on commercially reasonable terms, if at all. Any of these circumstances may also force us to redesign our solutions if a component becomes unavailable in order to incorporate a component from an alternative source.

Our solutions incorporate multiple software components obtained from licensors on a non-exclusive basis, such as voice recognition software, software supporting the runtime execution of our software platform, and database and reporting software. Our license agreements can be terminated for cause. In many cases, these license agreements specify a limited term and are only renewable beyond that term with the consent of the licensor. If a licensor terminates a license agreement for cause, objects to its renewal, or conditions renewal on modified terms and conditions, we may be unable to obtain licenses for equivalent software components on reasonable terms and conditions, including licensing fees, warranties or protection from infringement claims. Some licensors may discontinue licensing their software to us or support of the software version used in our solutions. In such circumstances, we may need

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to redesign our solutions at substantial cost to incorporate alternative software components or be subject to higher royalty costs. Any of these circumstances could adversely affect the cost and availability of our solutions.

Third-party licensors generally require us to incorporate specific license terms and conditions in our agreements with our customers. If we are alleged to have failed to incorporate these license terms and conditions, we may be subject to claims by these licensors, incur significant legal costs defending ourselves against such claims and, if such claims are successful, be subject to termination of licenses, monetary damages, or an injunction against the continued distribution of one or more of our solutions.

Because we depend upon a contract manufacturer, our operations could be harmed and we could lose sales if we encounter problems with this manufacturer.

We do not have internal manufacturing capabilities and rely upon a contract manufacturer, SMTC Corporation, to produce the primary hardware component of our Voice Communication solution. We have entered into a manufacturing agreement with SMTC that is terminable by either party with advance notice and that may also be terminated for a material uncured breach. We also rely on original design manufacturers, or ODMs, to produce accessories, including batteries, chargers and attachments. If SMTC or an ODM is unable or unwilling to continue manufacturing components of our solutions in the volumes that we require, fails to meet our quality specifications or significantly increases its prices, we may not be able to deliver our solution to our customers with the quantities, quality and performance that they expect in a timely manner. As a result, we could lose sales and our operating results could be harmed.

SMTC or ODMs may experience problems that could impact the quantity and quality of components of our Voice Communication solution, including disruptions in their manufacturing operations due to equipment breakdowns, labor strikes or shortages, component or material shortages and cost increases. SMTC and these ODMs generally rely on purchase orders rather than long-term contracts with their suppliers, and as a result, may not be able to secure sufficient components or other materials at reasonable prices or of acceptable quality to build components of our solutions in a timely manner. The majority of the components of our Voice Communication solution are manufactured in Asia or Mexico and adverse changes in political or economic circumstances in those locations could also disrupt our supply and quality of components of our solutions. In October 2011, we introduced the B3000 badge. Initial production of this product has commenced with SMTC in the United States, with production transitioning to Mexico in 2012. Companies occasionally encounter unexpected difficulties in ramping up to volume production of new products, and we may experience such difficulties with the B3000 badge. SMTC and our ODMs also manufacture products for other companies. Generally, our orders represent a relatively small percentage of the overall orders received by SMTC and these ODMs from their customers; therefore, fulfilling our orders may not be a priority in the event SMTC or an ODM is constrained in its ability to fulfill all of its customer obligations. In addition, if SMTC or an ODM is unable or unwilling to continue manufacturing components of our solutions, we may have to identify one or more alternative manufacturers. The process of identifying and qualifying a new contract manufacturer or ODM can be time consuming, and we may not be able to substitute suitable alternative manufacturers in a timely manner or at an acceptable cost. Additionally, transitioning to a new manufacturer may cause us to incur additional costs and delays if the new manufacturer has difficulty manufacturing components of our solutions to our specifications or quality standards.

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If we fail to forecast our manufacturing requirements accurately, or fail to properly manage our inventory with our contract manufacturer, we could incur additional costs and experience manufacturing delays, which can adversely affect our operating results.

We place orders with our contract manufacturer, SMTC, and we and SMTC place orders with suppliers based on forecasts of customer demand. Because of our international low cost sourcing strategy, our lead times are long and cause substantially more risk to forecasting accuracy than would result were lead times shorter. Our forecasts are based on multiple assumptions, each of which may introduce errors into our estimates affecting our ability to meet our customers’ demands for our solutions. If demand for our solutions increases significantly, we may not be able to meet demand on a timely basis, and we may need to expend a significant amount of time working with our customers to allocate limited supply and maintain positive customer relations, or we may incur additional costs in order to expedite the manufacture and delivery of additional inventory. If we underestimate customer demand, our contract manufacturer may have inadequate materials and subcomponents on hand to produce components of our solutions, which could result in manufacturing interruptions, shipment delays, deferral or loss of revenue, and damage to our customer relationships. Conversely, if we overestimate customer demand, we and SMTC may purchase more inventory than required for actual customer orders, resulting in excess or obsolete inventory, thereby increasing our costs and harming our operating results.

If hospitals do not have and are not willing to install the wireless infrastructure required to operate our Voice Communication solution, then they may experience technical problems or not purchase our solution at all.

The effectiveness of our Voice Communication solution depends upon the quality and compatibility of the communications environment of our healthcare customers. Our solutions require voice-grade wireless, or Wi-Fi, installed through large enterprise environments, which can vary from hospital to hospital and from department to department within a hospital. Many hospitals have not installed a voice-grade wireless infrastructure. If potential customers do not have a wireless network that can properly and fully interoperate with our Voice Communication solution, then such a network must be installed, or an existing Wi-Fi network must be upgraded, for example, by adding access points in stairwells, for our Voice Communication solution to be fully functional. The additional cost of installing or upgrading a Wi-Fi network may dissuade potential customers from installing our solution. Furthermore, if changes to a customer’s physical or information technology environment cause integration issues or degrade the effectiveness of our solution, or if the customer fails to upgrade its environment as may be required for software releases or updates, the customer may not be able to fully utilize our solution or may experience technical problems. If such circumstances arise, prospective customers may not purchase or existing customers may not expand their use of or deploy upgraded versions of our Voice Communication solution, thereby harming our business and operating results.

If we fail to achieve certification for certain U.S. federal standards, our sales to U.S. government customers will suffer.

We believe that a significant opportunity exists to sell our products to healthcare facilities in the Veterans Administration and Department of Defense, or DoD. These customers require independent certification of compliance with particular requirements relating to encryption, security, interoperability and scalability. These requirements include compliance with Federal Information Processing Standard, or FIPS, 140-2 and, as to DoD facilities, certification by the Joint Interoperability and Test Command, or JITC, of DoD and under the DoD Information Assurance

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Certification and Accreditation Process, or DIACAP. We are in the process of completing full certification of our Voice Communication solution under these standards for use with the B2000 badge, and will undertake to achieve certification for the B3000 badge and future products as well. A failure on our part to comply in a timely manner with these requirements, both as to current products and as to new product versions, could adversely impact our revenue.

We plan to opportunistically expand our communications solutions in non-healthcare markets, but this expansion may not be successful.

We are currently focused on selling our communications solutions to the healthcare market. We are evaluating how to further serve non-healthcare markets, but we plan to address non-healthcare markets opportunistically. We may not be successful in further penetrating the current non-healthcare markets we serve or in selling our solutions to new markets. Our Voice Communication solution has been deployed in over 100 customers in non-healthcare markets, including hospitality, retail and libraries. Total revenue from non-healthcare customers accounted for 2.9% of our revenue in 2011. If we cannot maintain these customers by providing communications solutions that meet their requirements, if we cannot successfully expand our communications solutions in non-healthcare markets, or if our solutions are adopted more slowly than we anticipate, we may not obtain significant revenue from these markets. We may experience challenges as we expand in non-healthcare markets, including pricing pressure on our solutions and technical issues as we adapt our solutions for the requirements of new markets. Our communications solutions also may not contain the functionality required by these non-healthcare markets or may not sufficiently differentiate us from competing solutions such that customers can justify deploying our solutions.

If we fail to successfully develop and introduce new solutions and features to existing solutions, our revenue, operating results and reputation could suffer.

Our success depends, in part, upon our ability to develop and introduce new solutions and features to existing solutions that meet existing and new customer requirements. We may not be able to develop and introduce new solutions or features on a timely basis or in response to customers’ changing requirements, or that sufficiently differentiate us from competing solutions such that customers can justify deploying our solutions. We may experience technical problems and additional costs as we introduce new features to our software platform, deploy future models of our wireless badges and integrate new solutions with existing customer clinical systems and workflows. In addition, we may face technical difficulties as we expand into non-English speaking countries and incorporate non-English speech recognition capabilities into our Voice Communication solution. Our recently introduced B3000 badge will reduce demand for our existing B2000 badges, and we must therefore successfully manage the transition from existing badges, avoid excessive inventory levels and ensure that sufficient supplies of new badges can be delivered to meet customer demand. We also may incur substantial costs or delays in the manufacture of the B3000 badge and any additional new products or models as we seek to optimize production methods and processes at our contract manufacturer. In addition, we expect that we will at least initially achieve lower gross margins on new models, while endeavoring to reduce manufacturing costs over time. If any of these problems were to arise, our revenue, operating results and reputation could suffer.

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If we do not achieve the anticipated strategic or financial benefits from our acquisitions or if we cannot successfully integrate them, our business and operating results could be harmed.

We have acquired, and in the future may acquire, complementary businesses, technologies or assets that we believe to be strategic, such as our four acquisitions completed in 2010. We may not achieve the anticipated strategic or financial benefits, or be successful in integrating any acquired businesses, technologies or assets. If we cannot effectively integrate our Voice Communication solution with our new Messaging and Care Transition solutions and successfully market and sell these solutions, we may not achieve market acceptance for, or significant revenue from, these new solutions.

Integrating newly acquired businesses, technologies and assets could strain our resources, could be expensive and time consuming, and might not be successful. Our recent acquisitions expose us, and if we acquire or invest in additional businesses, technologies or assets, we will be further exposed, to a number of risks, including that we may:

In addition, from time to time we may enter into negotiations for acquisitions that are not ultimately consummated. These negotiations could result in significant diversion of management time, as well as substantial out-of-pocket costs. If we were to proceed with one or more significant acquisitions in which the consideration included cash, we could be required to use a substantial portion of our available cash, including the proceeds of this offering. To the extent we issue shares of capital stock or other rights to purchase capital stock, including options and warrants, the ownership of existing stockholders would be diluted. In addition, acquisitions may result in the incurrence of debt, contingent liabilities, large write-offs, or other unanticipated costs, events or circumstances, any of which could harm our operating results.

If we are not able to manage our growth effectively, or if our business does not grow as we expect, our operating results will suffer.

We have experienced significant revenue growth in a short period of time. Our revenue increased from $41.1 million for 2009 to $79.5 million for 2011. During these periods, we significantly expanded our operations and more than doubled the number of our employees from 123 as of January 1, 2009 to 290 as of December 31, 2011.

Our rapid growth has placed, and will continue to place, a significant strain on our management systems, infrastructure and other resources. We plan to hire additional direct sales and marketing

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personnel domestically and internationally, acquire complementary businesses, technologies or assets, and increase our investment in research and development. Our future operating results depend to a large extent on our ability to successfully implement these plans and manage our anticipated expansion. To do so successfully we must, among other things:

We anticipate implementing a new enterprise resource planning application, or ERP, beginning in 2012. We may experience difficulties in implementing the ERP, and we may fail to gain the efficiencies the implementation is designed to produce. The implementation could also be disruptive to our operations, including the ability to timely ship and track product orders to our customers, project inventory requirements, manage our supply chain and otherwise adequately service our customers.

We expect to incur costs associated with the investments made to support our growth before the anticipated benefits or the returns are realized, if at all. If we are unable to manage our growth effectively, we may not be able to take advantage of market opportunities or develop new solutions or enhancements to existing solutions. We may also fail to satisfy customer requirements, maintain quality, execute our business plan or respond to competitive pressures, which could result in lower revenue and a decline in the share price of our common stock.

We generally recognize revenue from maintenance and support contracts over the contract term, and changes in sales may not be immediately reflected in our operating results.

We generally recognize revenue from our customer maintenance and support contracts ratably over the contract term, which is typically 12 months, in some cases subject to an early termination right. For 2010 and 2011, revenue from our maintenance and support contracts accounted for 30.7% and 27.0% of our revenue, respectively. A portion of the revenue we report in each quarter is derived from the recognition of deferred revenue relating to maintenance and support contracts entered into during previous quarters. Consequently, a decline in new or renewed maintenance and support by our customers in any one quarter may not be immediately reflected in our revenue for that quarter. Such a decline, however, will negatively affect our revenue in future quarters. Accordingly, the effect of significant downturns in sales and market acceptance of our services and potential changes in our rate of renewals may not be fully reflected in our operating results until future periods.

Our revenue and operating results have fluctuated, and are likely to continue to fluctuate, which may make our quarterly results difficult to predict, cause us to miss analyst expectations and cause the price of our common stock to decline.

Our operating results may be difficult to predict, even in the near term, and are likely to fluctuate as a result of a variety of factors, many of which are outside of our control. We have historically obtained substantially all of our revenue from the sale of our Voice Communication

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solution, which we anticipate will represent the most significant portion of our revenue for the foreseeable future, as we only recently began offering our Messaging and Care Transition solutions.

Comparisons of our revenue and operating results on a period-to-period basis may not be meaningful. You should not rely on our past results as an indication of our future performance. Each of the following factors, among others, could cause our operating results to fluctuate from quarter to quarter:

Our success depends upon our ability to attract, integrate and retain key personnel, and our failure to do so could harm our ability to grow our business.

Our success depends, in part, on the continuing services of our senior management and other key personnel, including in particular our executive officers and co-founder, as identified under “Management—Executive officers and directors,” and our ability to continue to attract, integrate and retain highly skilled personnel, particularly in engineering, sales and marketing. Competition for highly skilled personnel is intense, particularly in the Silicon Valley where our headquarters are located. If we fail to attract, integrate and retain key personnel, our ability to grow our business could be harmed.

The members of our senior management and other key personnel are at-will employees, and may terminate their employment at any time without notice. If they terminate their employment, we may not be able to find qualified individuals to replace them on a timely basis or at all and our senior management may need to divert their attention from other aspects of our business. Former employees may also become employees of a competitor. We may also have to pay additional compensation to attract and retain key personnel. We also anticipate hiring additional engineering, marketing and sales personnel to grow our business. Often, significant amounts of time and resources are required to train these personnel. We may incur significant costs to attract, integrate and retain them, and we may lose them to a competitor or another company before we realize the benefit of our investments in them.

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We primarily compete in the rapidly evolving and competitive healthcare market, and if we fail to effectively respond to competitive pressures, our business and operating results could be harmed.

We believe that at this time the primary competition for our Voice Communication solution consists of traditional methods using wired phones, pagers and overhead intercoms. While we believe that our system is superior to these legacy methods, our solution requires a significant infrastructure investment by a hospital and many hospitals may not recognize the value of implementing our solution.

Manufacturers and distributors of product categories such as cellular phones, pagers, mobile radios, and in-building wireless telephones attempt to sell their products to hospitals as components of an overall communication system. Of these product categories, in-building wireless telephones represent the most significant competition for the sale of our solution. The market for in-building wireless phones is dominated by large horizontal communications companies such as Cisco Systems, Ascom and Polycom. In addition, while smartphones and tablets are not at present direct competitors, their proliferation may make them a de facto standard for hospital workflow, thereby making our solution less attractive to customers.

While we do not have a directly comparable competitor that provides a richly featured voice communication system for the healthcare market, we could face such competition in the future. Potential competitors in the healthcare or communications markets include large, multinational companies with significantly more resources to dedicate to product development and sales and marketing. These companies may have existing relationships within the hospital, which may enhance their ability to gain a foothold in our market. Customers may prefer to purchase a more highly integrated or bundled solution from a single provider or an existing supplier rather than a new supplier, regardless of performance or features.

Accordingly, if we fail to effectively respond to competitive pressures, we could experience pricing pressure, reduced profit margins, higher sales and marketing expenses, lower revenue and the loss of market share, any of which would harm our business, operating results or financial condition.

Our international operations subject us, and may increasingly subject us in the future, to operational, financial, economic and political risks abroad.

Although we derive a relatively small portion of our revenue from customers outside the United States, we believe that non-U.S. customers could represent an increasing share of our revenue in the future. During 2010 and 2011, we obtained 9.7% and 7.3% of our revenue, respectively, from customers outside of the United States, including Canada, the United Kingdom, Australia, the Republic of Ireland and New Zealand. Accordingly, we are subject to risks and challenges that we would not otherwise face if we conducted our business solely in the United States, including:

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Any of these factors could harm our existing international business, impair our ability to expand into international markets or harm our operating results.

Our Voice Communication solution is highly complex and may contain undetected software or hardware errors that could harm our reputation and operating results.

Our Voice Communication solution incorporates complex technology, is deployed in a variety of complex hospital environments and must interoperate with many different types of devices and hospital systems. While we test the components of our solutions for defects and errors prior to release, we or our customers may not discover a defect or error until after we have deployed our solution, integrated it into the hospital environment and our customer has commenced general use of the solution. For example, in 2005, a prior model of our wireless badge, the B1000, was affected by chipset compatibility issues with certain wireless access points at customer facilities, resulting in our exchanging a large percentage of deployed badges for new badges. We did this exchange at no cost to our customers, thereby incurring substantial costs. In addition, our solutions in some cases are integrated with hardware and software offered by “middleware” vendors in order to interoperate with nurse call systems, device alarms and other hospital systems. If we cannot successfully integrate our solution with these vendors as needed or if any hardware or software of these vendors contains any defect or error, then our solution may not perform as designed, or may exhibit a defect or error.

Any defects or errors in, or which are attributed to, our solutions, could result in:

If any of these occur, our operating results and reputation could be harmed.

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We face potential liability related to the privacy and security of personal information collected through our solutions.

In connection with our healthcare communications business, we may handle or have access to personal health information subject in the United States to the Health Insurance Portability and Accountability Act of 1996, or HIPAA, the Health Information Technology for Economic and Clinical Health Act of 2009, or HITECH, regulations issued pursuant to these statutes, state privacy and security laws and regulations, and associated contractual obligations as a “business associate” of healthcare providers. These statutes and regulations impose numerous requirements regarding the use and disclosure of personal health information with which we must comply. Our failure to accurately anticipate the application or interpretation of these laws and regulations as we develop our solutions or a failure by us to comply with their requirements (e.g., evolving encryption and security requirements) could create material civil and/or criminal liability for us, resulting in adverse publicity and negatively affecting our business.

In addition, the use and disclosure of personal health information is subject to regulation in other jurisdictions in which we do business or expect to do business in the future. Those jurisdictions may attempt to apply such laws extraterritorially or through treaties or other arrangements with U.S. governmental entities. We might unintentionally violate such laws, such laws may be modified and new laws may be enacted in the future which may increase the chance that we violate them. Any such developments, or developments stemming from enactment or modification of other laws, or the failure by us to comply with their requirements or to accurately anticipate the application or interpretation of these laws could create material liability to us, result in adverse publicity and negatively affect our business.

For example, the European Union, or EU, adopted the Data Protection Directive, or DPD, imposing strict regulations and establishing a series of requirements regarding the storage of personally identifiable information on computers or recorded on other electronic media. This has been implemented by all EU member states through national laws. DPD provides for specific regulations requiring all non-EU countries doing business with EU member states to provide adequate data privacy protection when receiving personal data from any of the EU member states. Similarly, Canada’s Personal Information and Protection of Electronic Documents Act provides Canadian residents with privacy protections in regard to transactions with businesses and organizations in the private sector and sets out ground rules for how private sector organizations may collect, use and disclose personal information in the course of commercial activities. A finding that we have failed to comply with applicable laws and regulations regarding the collection, use and disclosure of personal information could create liability for us, result in adverse publicity and negatively affect our business.

Any legislation or regulation in the area of privacy and security of personal information could affect the way we operate our services and could harm our business. The costs of compliance with, and the other burdens imposed by, these and other laws or regulatory actions may prevent us from selling our solutions or increase the costs associated with selling our solutions, and may affect our ability to invest in or jointly develop solutions in the United States and in foreign jurisdictions. Further, we cannot assure you that our privacy and security policies and practices will be found sufficient to protect us from liability or adverse publicity relating to the privacy and security of personal information.

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Developments in the healthcare industry and governing regulations could negatively affect our business.

Substantially all of our revenue is derived from customers in the healthcare industry, in particular, hospitals. The healthcare industry is highly regulated and is subject to changing political, legislative, regulatory and other influences. Developments generally affecting the healthcare industry, including new regulations or new interpretations of existing regulations, could adversely affect spending on information technology and capital equipment by reducing funding, changes in healthcare pricing or delivery, or creating impediments for obtaining healthcare reimbursements, thereby causing our sales to decline and negatively impacting our business. For example, the profit margins of our hospital customers are modest and pending changes in reimbursement for healthcare costs may reduce the overall solvency of our customers or cause further deterioration in their financial or business condition.

In March 2010, the United States enacted comprehensive healthcare reform legislation through the Patient Protection and Affordable Health Care for America Act and the Health Care and Education Reconciliation Act. The new law is expected to increase the number of Americans with health insurance coverage by approximately 32 million through individual and employer mandates, subsidies offered to lower income individuals with smaller employers and broadening of Medicaid eligibility, and to affect healthcare reimbursement levels for healthcare providers. We cannot predict with certainty what the ultimate effect of federal healthcare reform or any future legislation or regulation, or healthcare initiatives, if any, implemented at the state level, will have on us or our customers. For example, the federal healthcare reform imposes a 2.3% excise tax on medical devices beginning January 2013, to which our company would be subject if any of our communications solutions are classified as medical devices. The impact of the tax, coupled with reform-associated payment reductions to Medicare and Medicaid reimbursement, could harm our business, operating results and cash flows.

In addition, our customers’ expectations regarding pending or potential industry developments may also affect their budgeting processes and spending plans with respect to our communications solutions. The healthcare industry has changed significantly in recent years and we expect that significant changes will continue to occur. However, the timing and impact of developments in the healthcare industry are difficult to predict. We cannot assure you that the markets for our solutions will continue to exist at current levels or that we will have adequate technical, financial and marketing resources to react to changes in those markets.

Our use of open source and non-commercial software components could impose risks and limitations on our ability to commercialize our solutions.

Our solutions contain software modules licensed under open source and other types of non-commercial licenses, including the GNU Public License, the GNU Lesser Public License, the Apache License and others. We also may incorporate open source and other licensed software into our solutions in the future. Use and distribution of such software may entail greater risks than use of third-party commercial software, as licenses of these types generally do not provide warranties or other contractual protections regarding infringement claims or the quality of the code. Some of these licenses require the release of our proprietary source code to the public if we combine our proprietary software with open source software in certain manners. This could allow competitors to create similar products with lower development effort and time and ultimately result in a loss of sales for us.

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The terms of many open source and other non-commercial licenses have not been interpreted by U.S. courts, and there is a risk that such licenses could be construed in a manner that could impose unanticipated conditions or restrictions on our ability to commercialize our solutions. In such event, in order to continue offering our solutions, we could be required to seek licenses from alternative licensors, which may not be available on a commercially reasonable basis or at all, to re-engineer our solutions or to discontinue the sale of our solutions in the event we cannot obtain a license or re-engineer our solutions on a timely basis, any of which could harm our business and operating results. In addition, if an owner of licensed software were to allege that we had not complied with the conditions of the corresponding license agreement, we could incur significant legal costs defending ourselves against such allegations. In the event such claims were successful, we could be subject to significant damages, be required to disclose our source code, or be enjoined from the distribution of our solutions.

Claims of intellectual property infringement could harm our business.

Vigorous protection and pursuit of intellectual property rights has resulted in protracted and expensive litigation for many companies in our industry. Although claims of this kind have not materially affected our business to date, there can be no assurance of the absence of such claims in the future. Any claims or proceedings against us, whether meritorious or not, could be time consuming, result in costly litigation, require significant amounts of management time, result in the diversion of significant operational resources, or require us to enter into royalty or licensing agreements, any of which could harm our business and operating results.

Intellectual property lawsuits are subject to inherent uncertainties due to the complexity of the technical issues involved, and we cannot be certain that we will be successful in defending ourselves against intellectual property claims. In addition, we currently have a limited portfolio of issued patents compared to many other industry participants, and therefore may not be able to effectively utilize our intellectual property portfolio to assert defenses or counterclaims in response to patent infringement claims or litigation brought against us by third parties. Further, litigation may involve patent holding companies or other adverse patent owners who have no relevant products and against whom our potential patents may provide little or no deterrence. Many potential litigants have the capability to dedicate substantially greater resources to enforce their intellectual property rights and to defend claims that may be brought against them. Furthermore, a successful claimant could secure a judgment that requires us to pay substantial damages or prevents us from distributing certain solutions or performing certain services. We might also be required to seek a license and pay royalties for the use of such intellectual property, which may not be available on commercially acceptable terms or at all. Alternatively, we may be required to develop non-infringing technology, which could require significant effort and expense and may ultimately not be successful.

If we are unable to protect our intellectual property rights, our competitive position could be harmed or we could be required to incur significant expenses to enforce our rights.

Our success depends, in part, on our ability to protect our proprietary technology. We protect our proprietary technology through patent, copyright, trade secret and trademark laws in the United States and similar laws in other countries. We also protect our proprietary technology through licensing agreements, nondisclosure agreements and other contractual provisions. These protections may not be available in all cases or may be inadequate to prevent our competitors from copying, reverse engineering or otherwise obtaining and using our technology, proprietary rights or solutions in an unauthorized manner. The laws of some foreign countries may not be as

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protective of intellectual property rights as those in the United States, and mechanisms for enforcement of intellectual property rights may be inadequate. In addition, third parties may seek to challenge, invalidate or circumvent our patents, trademarks, copyrights and trade secrets, or applications for any of the foregoing. Our competitors may independently develop technologies that are substantially equivalent, or superior, to our technology or design around our proprietary rights. In each case, our ability to compete could be significantly impaired.

To prevent unauthorized use of our intellectual property rights, it may be necessary to prosecute actions for infringement or misappropriation of our proprietary rights. Any such action could result in significant costs and diversion of our resources and management’s attention, and there can be no assurance that we will be successful in such action. Furthermore, many of our current and potential competitors have the ability to dedicate substantially greater resources to enforce their intellectual property rights than we. Accordingly, despite our efforts, we may not be able to prevent third parties from infringing or misappropriating our intellectual property.

While we plan to continue to protect our intellectual property with, among other things, patent protection, there can be no assurance that:

Our failure to obtain patents with claims of a scope necessary to cover our technology, or the invalidation of our patents, or our inability to protect any of our intellectual property, may weaken our competitive position and harm our business and operating results.

We might be required to spend significant resources to monitor and protect our intellectual property rights. We may initiate claims or litigation against third parties for infringement of our proprietary rights or to establish the validity of our proprietary rights. Any litigation, whether or not it is resolved in our favor, could result in significant expense to us and divert the efforts of our technical and management personnel, which may harm our business, operating results and financial condition.

Our solutions could be subject to regulation by the U.S. Food and Drug Administration or similar foreign agencies, which could increase our operating costs.

We provide devices that may be, or may become, subject to regulation by the U.S. Food and Drug Administration, or FDA, and similar agencies in other countries, or the jurisdiction of these agencies could be expanded in the future to include our solutions. The FDA regulates certain products, including software-based products, as “medical devices” based, in part, on the intended use of the product and the risk the device poses to the patient should the device fail to perform properly. Although we have concluded that our wireless badge is a general-purpose communications device not subject to FDA regulation, the FDA could disagree with our conclusion, or changes in our solutions or the FDA’s evolving regulation could lead to FDA

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regulation of our solutions. Many other countries in which we sell or may sell our solutions could also have similar regulations applicable to our solutions, some of which may be subject to change or interpretation. We may incur substantial operating costs if we are required to register our solutions or components of our solutions as regulated medical devices under U.S. or foreign regulations, obtain premarket approval from the FDA or foreign regulatory agencies, and satisfy the extensive reporting requirements. In addition, failure to comply with these regulations could result in enforcement actions and monetary penalties.

Product liability or other liability claims could cause us to incur significant costs, adversely affect the sales of our solutions and harm our reputation.

Our solutions are utilized by healthcare professionals and others in the course of providing patient care. It is possible that patients, family members, physicians or others may allege we are responsible for harm to patients due to defects in, or the malfunction of, our solutions. Any such allegations could harm our reputation and ability to sell our solutions. Components of our solutions utilizing Wi-Fi also emit radio frequency, or RF, energy. RF emissions have been alleged, in connection with cellular phones, to have adverse health consequences. While these components of our solutions comply with guidelines applicable to such emissions, some may allege that these components of our solutions cause adverse health consequences or applicable guidelines may change making these components of our solutions non-compliant. In addition, regulatory agencies in the United States and other countries in which we do or plan to do business may implement regulations concerning RF emissions standards. Any such allegations or non-compliance, or any regulatory changes affecting the transmission of radio signals could negatively impact the sales of our solutions, require costly modifications to our solutions and harm our reputation.

Although our customer agreements contain terms and conditions, including disclaimers of liability, that are intended to reduce or eliminate our potential liability, we could be required to spend significant amounts of management time and resources to defend ourselves against product liability, tort, warranty or other claims. If any such claims were to prevail, we could be forced to pay damages, comply with injunctions or stop distributing our solutions. Even if potential claims do not result in liability to us, investigating and defending against these claims could be expensive and time consuming and could divert management’s attention away from our business. We maintain general liability insurance coverage, including coverage for errors and omissions; however, this coverage may not be sufficient to cover large claims against us or otherwise continue to be available on acceptable terms. Further, the insurer could attempt to disclaim coverage as to any particular claim.

Our business is subject to the risks of earthquakes, fire, floods and other natural catastrophic events, and to interruption by manmade problems such as power disruptions or terrorism.

Our corporate headquarters are located in the San Francisco Bay Area, a region known for seismic activity, and many critical components of our solutions are sourced in Asia, a region that has also suffered natural disasters. A significant natural disaster, such as an earthquake, fire or a flood, occurring at our headquarters, our other facilities or where our contract manufacturer or its suppliers are located, could harm our business, operating results and financial condition. In addition, acts of terrorism could cause disruptions in our business, the businesses of our customers and suppliers, or the economy as a whole. We also rely on information technology systems to communicate among our workforce located worldwide, and in particular, our senior management, general and administrative, and research and development activities that are coordinated with our corporate headquarters in the San Francisco Bay Area. Any disruption to

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our internal communications, whether caused by a natural disaster or by manmade problems, such as power disruptions, in the San Francisco Bay Area or Asia could delay our research and development efforts, cause delays or cancellations of customer orders or delay deployment of our solutions, which could harm our business, operating results and financial condition.

We may require additional capital to support our business growth, and such capital may not be available.

We intend to continue to make investments to support business growth and may require additional funds to respond to business challenges, which include the need to develop new solutions or enhance existing solutions, enhance our operating infrastructure, expand our sales and marketing capabilities, expand into non-healthcare markets, and acquire complementary businesses, technologies or assets. Accordingly, we may need to engage in equity or debt financing to secure funds in addition to our current debt facility. Equity and debt financing, however, might not be available when needed or, if available, might not be available on terms satisfactory to us. If we raise additional funds through equity financing, our stockholders may experience dilution. Debt financing, if available, may involve covenants restricting our operations or our ability to incur additional debt. If we are unable to obtain adequate financing or financing on terms satisfactory to us, our ability to continue to support our business growth and to respond to business challenges could be significantly limited as we may have to delay, reduce the scope of or eliminate some or all of our initiatives, which could harm our operating results.

We will incur increased costs as a result of operating as a public company and our management will have to devote substantial time to public company compliance obligations.

As a public company, we will incur significant legal, accounting and other expenses that we did not incur as a private company. The Sarbanes-Oxley Act of 2002, as well as rules subsequently implemented by the Securities and Exchange Commission, or SEC, and our stock exchange, has imposed various requirements on public companies, including requiring changes in corporate governance practices. Our management and other personnel will need to devote a substantial amount of time to these compliance requirements and any new requirements that the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 may impose on public companies. Moreover, these rules and regulations, along with compliance with accounting principles and regulatory interpretations of such principles, have increased and will continue to increase our legal, accounting and financial compliance costs and have made and will continue to make some activities more time-consuming and costly. For example, we expect these rules and regulations to make it more difficult and more expensive for us to obtain director and officer liability insurance, and we may be required to accept reduced policy limits and coverage or incur substantial costs to maintain the same or similar coverage. These rules and regulations could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors or our board committees, or as executive officers. We will evaluate the need to hire additional accounting and financial staff with appropriate public company experience and technical accounting and financial knowledge. We estimate the additional costs we expect to incur as a result of being a public company to be approximately $2.0 million annually.

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If we are not able to maintain effective internal control over financial reporting in the future, the accuracy and timeliness of our financial reporting may be adversely affected.

We have had material weaknesses in our internal control over financial reporting in the past. A material weakness is defined under the standards issued by the Public Company Accounting Oversight Board as a deficiency, or combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of our financial statements will not be prevented or detected and corrected on a timely basis.

In connection with our preparation of the financial statements for the year ended December 31, 2010 and the six months ended June 30, 2011, our independent registered public accounting firm identified adjustments to our financial statements which resulted from control deficiencies that we considered to be two material weaknesses in our internal control over financial reporting. These related to controls for the preparation of (1) the provision for income taxes, resulting from insufficient technical expertise in the area of tax accounting for acquisitions and resulted in audit adjustments to our income tax provision for the year ended December 31, 2010 and (2) the statement of cash flows, resulting from the insufficient review of supporting schedules used in the preparation of the statement for unpaid purchases of property and equipment, and resulted in revisions to the statement of cash flows for the six months ended June 30, 2011.

We remediated these material weaknesses by (1) replacing the firm we have historically retained for tax accounting with a firm with the requisite expertise and enhancing the level of review by our recently appointed corporate controller who has the requisite technical expertise and experience; and (2) implementing additional controls relating to the compilation of the underlying schedules and cash flow statement and adding more detailed reviews of the underlying cash flow statement schedules by our SEC reporting manager, and our recently appointed corporate controller.

The Sarbanes-Oxley Act requires, among other things, that we assess the effectiveness of our internal control over financial reporting annually and disclosure controls and procedures quarterly. In particular, beginning with the year ending on December 31, 2013, we must perform system and process evaluation and testing of our internal control over financial reporting to allow management to report on, and our independent registered public accounting firm to attest to, the effectiveness of our internal control over financial reporting, as required by Section 404 of the Sarbanes-Oxley Act. If other material weaknesses are identified in the future or we are not able to comply with the requirements of Section 404 in a timely manner, our reported financial results could be materially misstated or could be restated, we could receive an adverse opinion regarding our controls from our accounting firm and we could be subject to investigations or sanctions by regulatory authorities, which would require additional financial and management resources, and the market price of our stock could decline.

The market size estimate included in this prospectus may prove to be inaccurate, and, as such, may not be reflective of our capacity for future growth.

The healthcare market has not yet broadly adopted an intelligent voice communication system similar to our Voice Communication solution. This being the case, although the market size estimate included in this prospectus is based on assumptions and estimates we believe to be reasonable, this estimate may not prove to be accurate. This is particularly the case with respect to estimating the size of the international component of the market. Even if the market is of the size we estimate, this market size may not be a meaningful estimate of the market opportunity that will prove to be available to us for a number of reasons, including those matters identified in these risk factors.

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Risks related to this offering

The market price of our common stock may be volatile, and your investment in our stock could suffer a decline in value.

We will determine the initial public offering price through negotiations with the underwriters and such price may not be indicative of future prices of our common stock, which may fluctuate significantly. There has been significant volatility in the market price and trading volume of equity securities, which is often unrelated or disproportionate to the financial performance of the companies issuing the securities. These broad market fluctuations may negatively affect the market price of our common stock. The market price of our common stock could fluctuate significantly in response to the factors described above and other factors, many of which are beyond our control, including:

In addition, in the past, following periods of volatility in the overall market and the market price of a particular company’s securities, securities class action litigation has often been instituted against these companies. This litigation, if instituted against us, could result in substantial costs and a diversion of our management’s attention and resources.

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No public market for our common stock currently exists, and an active trading market may not develop or be sustained following this offering.

Prior to this offering, there has been no public market for our common stock. Our common stock does not have any prior trading history. An active trading market may not develop following the closing of this offering or, if developed, may not be sustained. The lack of an active market may impair your ability to sell your shares at the time you wish to sell them or at a price that you consider reasonable. The lack of an active market may also reduce the fair market value of your shares. An inactive market may also impair our ability to raise capital to continue to fund operations by selling shares and may impair our ability to acquire other companies or technologies by using our shares as consideration.

If securities or industry analysts issue an adverse or misleading opinion regarding our stock or do not publish research or reports about our business, our stock price could decline.

The trading market for our common stock will depend in part on the research and reports that securities or industry analysts publish about us and our business. We do not control these analysts or the content and opinions included in their reports. The price of our common stock could decline if one or more analysts downgrade our common stock or if those analysts issue other unfavorable commentary or cease publishing reports about us or our business. If one or more analysts cease coverage of our company or fail to regularly publish reports about our company, we could lose visibility in the financial market, which in turn could cause our stock price to decline. Further, securities or industry analysts may elect not to provide research coverage of our common stock and such lack of research coverage may adversely affect the market price of our common stock.

The concentration of our capital stock ownership with insiders upon the closing of this offering will likely limit your ability to influence corporate matters.

We anticipate that our executive officers, directors, current 5% or greater stockholders and entities affiliated with any of them will together beneficially own approximately     % of our common stock outstanding after this offering, assuming the underwriters do not exercise their option to purchase additional shares. These stockholders, if they act together, will have significant influence over all matters requiring stockholder approval, including the election of directors and approval of significant corporate transactions, and may take actions that may not be in the best interests of our other stockholders. This concentration of ownership could also limit stockholders’ ability to influence corporate matters. Accordingly, corporate actions might be taken even if other stockholders, including those who purchase shares in this offering, oppose them, or may not be taken even if other stockholders view them as in the best interests of our stockholders. This concentration of ownership may have the effect of delaying or preventing a change of control of our company, may make the approval of certain transactions difficult or impossible without the support of these stockholders and might adversely affect the market price of our common stock.

Our management will have broad discretion over the use of proceeds from this offering and might not apply the proceeds of this offering in ways that increase the value of your investment.

Our management will have broad discretion to use the net proceeds to us from this offering, and you will be relying on the judgment of our management regarding the application of these proceeds, without the opportunity, as part of your investment decision, to assess whether the

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proceeds are being used appropriately. The failure of our management to apply the net proceeds of our initial public offering effectively could harm our business, financial condition and operating results, and may not increase the value of your investment.

We have not allocated these net proceeds for specific purposes other than to repay in full outstanding borrowings under our credit facility. We intend to use the net proceeds from this offering for general corporate and working capital purposes as outlined in the section titled “Use of proceeds” elsewhere in this prospectus. We may also use a portion of the net proceeds to acquire or invest in complementary businesses, technologies or assets, but at this time, we have no current understandings, agreements or commitments to do so. Our management might not be able to yield a significant return or any return on any investment of these net proceeds.

Future sales of shares by existing stockholders could cause our stock price to decline.

If our existing stockholders sell, or indicate an intention to sell, substantial amounts of our common stock in the public market, or if it is perceived by the market that these sales might occur, the trading price of our common stock could decline. Based upon the number of shares outstanding as of                     , 2011, upon the closing of this offering, we will have              shares of common stock outstanding, assuming no exercise of our outstanding options and warrants.

All of the common stock sold in this offering will be freely tradable without restrictions or further registration under the Securities Act of 1933, as amended, referred to as the Securities Act, except for any shares held by our affiliates as defined in Rule 144 under the Securities Act. The remaining              shares of common stock outstanding after this offering, based on shares outstanding as of                     , 2011, will be restricted as a result of applicable securities laws, lock-up agreements or other contractual restrictions that restrict transfers for at least 180 days after the date of this prospectus, subject to certain extensions.

J.P. Morgan Securities LLC and Piper Jaffray & Co. may, in their sole discretion, release all or some portion of the shares subject to lock-up agreements with the underwriters prior to expiration of the lock-up period.

The holders of              shares of common stock, and holders of warrants to purchase 1,279,885 shares of common stock will be entitled to rights with respect to registration of such shares under the Securities Act pursuant to an investor rights agreement between such holders and us. If such holders, by exercising their registration rights, sell a large number of shares, they could adversely affect the market price for our common stock. If we file a registration statement for the purpose of selling additional shares to raise capital and are required to include shares held by these holders pursuant to the exercise of their registration rights, our ability to raise capital may be impaired.

We intend to file a registration statement under the Securities Act to register              shares for issuance under our equity incentive and employee stock purchase plans. Each of our 2011 Equity Incentive Plan and 2011 Employee Stock Purchase Plan provides for annual automatic increases in the shares reserved for issuance under the plan without stockholder approval, which would result in additional dilution to our stockholders. Once we register these shares, they can be freely sold in the public market upon issuance and vesting, subject to any applicable lock-up period or other restrictions provided under the terms of the applicable plan and/or the option agreements entered into with option holders.

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You will experience immediate and substantial dilution in the net tangible book value of the shares you purchase in this offering.

The assumed initial public offering price is substantially higher than the net tangible book value per share of our outstanding common stock will be immediately after this offering. If you purchase our common stock in this offering, you will suffer immediate and substantial dilution of $             per share based on the assumed initial public offering price of $             per share, the midpoint of the price range set forth on the cover page of this prospectus. If outstanding options and warrants to purchase our common stock are exercised, you will experience additional dilution. For a further description of the dilution that you will experience immediately after this offering, see the section titled “Dilution.”

We have never paid cash dividends on our capital stock, and we do not anticipate paying any dividends in the foreseeable future.

We have never paid cash dividends on any of our classes of capital stock and currently intend to retain our future earnings to fund the development and growth of our business. As a result, capital appreciation, if any, of our common stock will be the sole source of gain for the foreseeable future. In addition, our credit facility and security agreement restrict our ability to pay dividends.

Our charter documents and Delaware law could discourage, delay or prevent a change of control of our company or change in our management that stockholders consider favorable and cause our stock price to decline.

Certain provisions of our restated certificate of incorporation and restated bylaws to be effective upon the closing of this offering and Delaware law could discourage, delay or prevent a change of control of our company or change in our management that the stockholders of our company consider favorable. These provisions:

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Section 203 of the Delaware General Corporation Law may also discourage, delay or prevent a change of control of our company.

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Special note regarding forward-looking statements and industry data

This prospectus contains forward-looking statements that are based on our beliefs and assumptions regarding future events and circumstances, including statements regarding our strategies, our opportunities, developments in the healthcare market, our relationships with our customers and contract manufacturer and other matters. These statements are principally contained in the sections titled “Prospectus summary,” “Risk factors,” “Use of proceeds,” “Management’s discussion and analysis of financial condition and results of operations,” “Business,” “Executive compensation—Compensation discussion and analysis,” and “Shares eligible for future sale.” Forward-looking statements include statements that are not historical facts and can be identified by words such as “project,” “believe,” “anticipate,” “plan,” “expect,” “estimate,” “intend,” “continue,” “should,” “would,” “could,” “potentially,” “will” or “may,” or other similar words and phrases.

Forward-looking statements are subject to known and unknown risks, uncertainties and other factors that could cause actual results to differ materially from the results anticipated by these forward-looking statements. These risks, uncertainties and factors include those we discuss in this prospectus in the section titled “Risk factors.” You should read these risk factors and the other cautionary statements made in this prospectus as being applicable to all related forward-looking statements wherever they appear in this prospectus. It is not possible for us to predict all risks that could affect us, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. Moreover, new risks emerge from time to time.

The forward-looking statements made in this prospectus relate only to events as of the date on which the statements are made. We undertake no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

You should read this prospectus and the documents we reference in this prospects and have filed with the SEC as exhibits to the registration statement of which this prospectus is a part with the understanding that our actual future results, levels of activity, performance and events and circumstances may be materially different from what we expect.

This prospectus also contains estimates and other statistical data that we obtained or derived from industry publications, surveys, forecasts and reports. These industry publications generally indicate that they have obtained their information from sources believed to be reliable, but do not guarantee the accuracy and completeness of their information. This information involves a number of assumptions and limitations, and you are cautioned not to give undue weight to these estimates. Although we have not independently verified the accuracy or completeness of the data contained in these industry publications and reports, based on our industry experience we believe that the publications are reliable and the conclusions contained in the publications and reports are reasonable.

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Use of proceeds

We estimate that we will receive net proceeds from the sale of              shares of common stock that we are selling in this offering of approximately $             million, based on an assumed initial public offering price of $             per share, the midpoint of the price range set forth on the cover page of this prospectus, after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us. If the underwriters exercise in full their option to purchase additional shares, we estimate that our net proceeds will be approximately $             million, after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us. We will not receive any proceeds from the sale of shares of our common stock by the selling stockholders.

Each $1.00 increase or decrease in the assumed initial public offering price would increase or decrease, as applicable, the net proceeds to us by $             million, assuming the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same and after deducting estimated underwriting discounts and commissions.

The principal purposes of this offering are to obtain additional capital, to create a public market for our common stock and to facilitate our future access to the public equity markets. As of the date of this prospectus, we cannot specify with certainty all of the particular uses of the net proceeds of this offering. We expect to use net proceeds of the offering to repay in full outstanding borrowings under our credit facility. Aggregate borrowings under the facility were $8.3 million as of December 31, 2011, of which $3.8 million bore interest at a rate of 4.75% per annum and $4.5 million bore interest at a rate of 4.25% per annum. We expect to use the balance of the net proceeds for general corporate purposes, including working capital. We may also use a portion of the net proceeds to acquire or invest in complementary businesses, technologies or assets. However, we have no present understandings, commitments or agreements to enter into any acquisitions or make any investments.

Our management will have significant flexibility in applying the net proceeds from this offering, and investors will be relying on the judgment of our management regarding the application of these net proceeds. Pending the uses described above, we intend to invest the net proceeds from this offering in short-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the United States government. The goal with respect to the investment of these net proceeds will be capital preservation and liquidity so that these funds are readily available to fund our operations.

Dividend policy

We have never declared or paid any cash dividends on our capital stock, and we do not currently intend to pay any cash dividends on our common stock for the foreseeable future. We expect to retain future earnings, if any, to fund the development and growth of our business. Any future determination to pay dividends on our common stock will be at the discretion of our board of directors and will depend upon, among other factors, our financial condition, operating results, current and anticipated cash needs, plans for expansion and other factors that our board of directors may deem relevant. In addition, our credit facility and security agreement restrict our ability to pay dividends.

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