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Dual-Mode Wireless: The Simplicity Of One, The Power Of The Network

By Tony Rybczynski


The vision is simple. Bring your office anywhere ensuring secure, consistent, reliable unified communications anytime, anywhere, and over any device. But a critical business reality for you, as a mobile professional today, is managing the price/performance tradeoffs among the multitude of communications devices and networks at your disposal. You might already be carrying one or more of these devices: a cell phone, a PDA, a Blackberry, a laptop and a pager and using a variety of networks to attempt to stay relatively connected.

Enter the dual mode mobility device. As a starter, it supports WiFi and next-generation public wireless based on CDMA 1xEVDO and GSM UMTS technologies, delivering broadband connectivity across the LAN and WAN. It allows you to have one integrated device in your pocket and leave some of these other devices at home. Whether evolving from a smart phone, telephony enabled PDA or messaging device, a dual mode mobile device comes in various form factors to meet your business needs supporting voice, data and maybe video; with various screen sizes; with or without a keyboard or keypad; and with a range of accessories. It is built on one of a number of operating systems including Microsoft Pocket PC, Blackberry OS, Symbian OS, and comes bundled with personal productivity tools. While it carries an incredible amount of technology in a small handprint, the power of a dual mode device comes from secure seamless operation with network-based applications such as telephony, e-mail and ultimately unified communications.

Secure Seamless Operation
There are three aspects to seamless operation that are driving dual mode devices: secure enterprise telephony heading towards Unified Communications, public/private roaming, and managing price/performance.

Unified Communications integrates real-time and near-real-time communications, including telephony, conferencing, instant messaging and presence, and various forms of collaboration (including optionally video) into a rich consistent set of capabilities. A consistent user experience ensures seamless feature operation (e.g., for directory and voicemail access, call logs, call management) across desktop and mobile devices. The lingua franca of Unified Communications is the Session Initiation Protocol (SIP). SIP is a signaling and control protocol standard for initiating sessions between and among users, independent of media being used. In this new world, the user is known by a single address, and the network does the rest. In the short term, this could be his or her business phone number; in the longer term it could be a SIP address of the form [email protected]. The user, whether on the road or in the office, has a high degree of personal control as to how incoming calls are handled based on caller, medi a used, and time of day. These capabilities are realized on dual-mode devices by tunneling data and SIP signaling over an IPSec VPN connection into the enterprise, independent of the voice path (i.e., cellular or VoIP).

Secure mobility includes roaming from floor to floor in a building or campus, across the city and around the world. WiFi is exploding across the enterprise. Roaming across converged wireless LANs, that support fast handoff and user authentication, is becoming a reality across campus networks. At the same time, WiFi hot spots have emerged in hotels, conference centers, airports, and coffee shops creating an opportunity for remote wireless access using VPN technology. Finally, second- and third-generation broadband wireless services have been introduced and are being expanded across the country. While manually changing from WiFi to public cellular is an option depending on where the user is, seamless roaming implies non-disruptive voice, data, and multimedia session operation with minimum impact on the user as he or she moves from in-building to public environments, and vice versa. Solutions that are providing seamless WiFi/public wireless two-way roaming services are emerging for enterprises and service pr oviders; these are based on some form of handoff server, which acts as a signaling anchor point for SIP sessions.

Managing price/performance is a major concern across the business. A key opportunity enabled through dual mode mobile devices is that they allow users, whenever in the range of a wireless LAN access point, to leverage the higher bandwidth offered by WiFi for IP telephony and data. Given that often the majority of cell phone voice calls are made and received within an enterprise site, there is a significant opportunity to lower the number of cell minutes used, and minimize roaming and wireless long-distance charges. Together, these serve to address the escalating costs associated with the increased use of public wireless services, while optimally leveraging these services and WiFi deployments.

Simply And Securely Connected
Dual mode mobile devices enhance productivity by enabling just-in-time communications across the virtual enterprise, whether the user is a campus worker or road warrior. They open the door for seamless roaming between private and public domains and deliver a consistent user experience wherever the user is and whatever the device he uses. They ensure business continuity at the end user level and provide the means to maximize price/performance of telephony, data, and multimedia applications across private and public networks. Would the simplicity of one combined with the power of the network improve your employee productivity and enhance customer service? Absolutely. IT

Tony Rybczynski is Director of Strategic Enterprise Technologies at Nortel. He has over 30 years experience in the application of packet network technology. For more information, please visit

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