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Feature Article
October 2004

The Future Of VoIP Goes Wireless

BY Tom Kershaw

Voice over Internet Protocol (VoIP) is one of the hottest and most hyped technologies in the communications industry. Businesses and consumers are already taking advantage of the cost savings and new features of making calls over a converged voice-data network, and the logical next step is to take those advantages to the wireless world. The potential impact of wireless VoIP on the communications market is enormous — market research firm ABI Research has forecasted that dual mode cellular/voice over WiFi enabled handsets will surpass 50 million by 2009 — accounting for seven percent of the overall handset market. Early adopters are already touting the benefits of using WiFi to make inexpensive phone calls, but is this truly a technology that will take off any time soon?

The Wireless VoIP Opportunity
Wireless VoIP theoretically has many advantages, including reduced cost for calls and higher-bandwidth data transfers versus a traditional cellular connection. WiFi networks cost a fraction of what traditional cell tower technology costs to deploy, and can be rolled out quickly without the detailed site reviews required to install radio towers. More importantly, wireless VoIP can actually dramatically improve call quality — especially in residential areas or office towers where traditional mobile network coverage is spotty. What does this mean for the average user? As the workforce moves to a flexible, non-static environment, wireless VoIP will allow employees to roam from mobile networks to WiFi-based home and office networks — using a single device to manage communications that currently traverses mobile, home, and office handsets. Within the United States, nearly five million homes already have a WiFi network installed — imagine if you could use the same handset both in your home for cheap IP-based calls, and then switch to cellular when you leave the building? Clearly, this technology has a lot to offer, from the enterprise to the average phone user.

Wireless VoIP offers potential savings by allowing companies to change the way they manage their phone systems. For example, instead of having voicemail, caller ID and e-mail separately, wireless VoIP will allow customers to retrieve all of their messages in one place, alleviating the pain of having different operators for different services and ultimately dealing with several bills at a time. Employees can also download software applications, enabling them to turn their phones into “mini-computers” and track inventory, or log onto the company’s intranet.

From a consumer perspective, the increased bandwidth from using a dual handset will potentially allow us to download video and movies, watch TV shows via on-demand technology and even videoconference with friends and family — all at speeds faster than cellular networks.

Mainstreaming Wireless VoIP
While the buzz is already building about the promise of wireless VoIP, there are still some issues to address before the technology goes mainstream. The biggest obstacles to making WiFi telephony a success are not that different from the early days of cell phones. Three main areas need addressing:

  • Handoff of calls between network platforms;
  • Cost of infrastructure to support calls; and
  • Security.

The primary issue is providing the ability to roam from a WiFi network back to the traditional cellular network without having a call dropped. For example, making a call with your WiFi-enabled handset at the office is relatively simple — but leaving your corporate WiFi network to drive home without dropping the call requires more complex network roaming capabilities. To make this happen, the infrastructure needs to be built up to support it, and this can be a costly and complex process. The traditional mobile network uses a complex set of signaling protocols based on SS7, while the WiFi segment of the call is controlled using VoIP protocols such as SIP. Seamless interworking between traditional SS7 protocols and VoIP signaling is required, in addition to the need to manage different codecs and processing methods for the actual voice traffic. Finally, since wireless VoIP networks are used like a computer, the phone system is vulnerable to the hacker attacks and viruses that Internet users experience — with the added vulnerabilities associated with WiFi. Many WiFi home users are not fully versed in security capabilities, and need plug-and-play methods of protecting their home networks once they become combination voice-data networks. Users of WiFi spots, especially public WiFi spots, will have to be reassured that voice and data communications are as secure as possible.

Deciding “How” and “When”
With the rise of VoIP, wireless VoIP is not far behind. According to industry analyst firm Gartner (, the cable industry alone is poised to add more than six million new VoIP subscribers by 2008 to the existing base of circuit-switched cable-telephony customers. Large carriers are starting to get into the mix to develop standards and figure out how to make the infrastructure work, an indication that this technology is more than just hype.

Companies are already starting to work on wireless VoIP solutions. Proxim, Avaya and Motorola formed a partnership to integrate a WiFi/VoIP/ Cellular platform, helping solve integration issues. VeriSign recently partnered with BridgePort Networks and several other platform providers to build a comprehensive hosted solution that includes VoIP and WiFi roaming services, authentication, security and inter-carrier settlement — thereby reducing the capital investment required to set up wireless VoIP.

Once reliable, roaming-friendly networks are built out, WiFi enabled handsets are broadly available, and the connections are as easy to make as with our standard cell phones, wireless VoIP will become a reality. In the meantime, early adopters in markets such as higher education and finance are already implementing wireless VoIP solutions within buildings.

Tom Kershaw is vice president, VoIP services at VeriSign.
For more information, please visit the company online at

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