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Seamless Roaming Nears Reality


VCC aims to provide carrier-supported, standards-based seamless roaming between cellular and Wi-Fi networks. This would let customers retain single-number and voicemail access beyond the range of conventional cellular networks, as long as there's an accessible Wi-Fi network. An alternative access method may increase customer satisfaction and could lead to greater use of phones in more places..

Although the VCC standard is led by the 3GPP standards body, MobileIgnite, a separate group led by vendor BridgePort Networks, is also a key driver. These groups are made up of wireless carriers and equipment vendors, as well as third-party vendors that tie all the pieces together. Enterprise PBX vendors don't play a part, as the standard is centered on carrier integration.

VCC, at least in its first iteration, falls short in addressing key enterprise features, such as data-session maintenance and supplementary service support (call waiting, call transfer and so on). It has a simplistic roaming algorithm and provides no integration with the enterprise PBX. On the other hand, it will drive the development and availability of carrier-grade SIP-based dual-mode handsets.

Be careful what you ask for. Enterprises have long wanted dual-mode Wi-Fi cellular phones to cut phone bills with the convenience of a single device. Carriers have had nothing to gain from that; in fact, North American wireless carriers have discouraged handset makers from developing Wi-Fi-enabled handsets and have gone out of their way to offer customized versions without Wi-Fi.

Now enterprises are going to get what they've asked for--sort of. A new plan will let enterprise users continue with a single device, but carriers won't lose those precious minutes. The VCC (voice-call continuity) initiative promises to provide seamless roaming between cellular and Wi-Fi networks, letting mobile phone users access the office network for mobile services.

This new standard arose within the carrier-centric 3GPP (Third Generation Partnership Project) and is built around SIP (Session Initiation Protocol). Due to be completed next month, VCC will drive the development and availability of carrier-grade, SIP-based dual-mode handsets, which third-party vendors can sell to enterprises.

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