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For True UC, Remember Smartphones: Page 3 of 4

What Do You Mean By 'Mobile'?

CIOs striving to marry two big initiatives with expensive, and unnecessary, overlap first must define what versions of mobile UC IT will support. If users travel far and wide, cellular network services will be the only option. For employees who spend most of their time in the office, a well-designed wireless LAN can provide a lower-cost and often higher-quality alternative.

At a high level, mobile UC systems can be grouped into three categories:

>> WLAN-based systems: While the vast majority of today's laptops and netbooks have WLAN capabilities, voice handsets that operate on Wi-Fi also are popular in some industries. The two largest suppliers are Cisco, with its 7921G and 7925G handsets, and Polycom-SpectraLink, with its 8000 series. These devices, which are geared primarily toward voice and support few mobile UC capabilities, have found acceptance in key verticals, including healthcare and big-box retail.

>> Dual-mode Wi-Fi/cellular: By using handsets capable of operating on either Wi-Fi or cellular (primarily GSM), these systems can hand off calls between the two networks with no disruption. By some estimates, 40% to 60% of cellular calls are made and received while the user is in the office--within range of the Wi-Fi network--so you could significantly reduce cellular charges and help with indoor reception issues. Virtually all smartphones now have Wi-Fi capability.

>> Cellular-only mobile UC: Vendors including Avaya, Cisco, IBM, and Microsoft have developed mobile UC products that work solely on cellular networks but provide a rich set of UC features, such as directory access and presence. Further, cellular-only systems support a much wider range of handsets, including BlackBerry and iPhone. The downside is that they lack the ability to operate over Wi-Fi.

These cellular-only mobile UC systems employ a software client that sits on the smartphone and uses the cellular data service to exchange signaling messages with the IP PBX system. Users can view the corporate directory (with presence status) over that path and receive voice-mail alerts, and when call are placed to their desk sets, their mobiles ring simultaneously and they can see caller names and numbers there as well. In essence, the cellular data service provides an out-of-band signaling channel to the user's mobile device to enable UC capabilities. Good cellular coverage within the building is essential; mobile operators are increasingly turning to in-building cellular repeaters, distributed antenna systems, and new technologies like femtocells to improve indoor reception.

If you support tablets, you'll want to take these into consideration too; we discuss decision points as well as architecting a voice-capable WLAN in our full report.