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Poised for Takeoff: Page 6 of 24

Software updates are performed via TFTP upon phone start-up. However, CCM does not push device configurations to phones automatically, though that capability is planned for a future release. And though Cisco has done a credible job of replicating the functionality of its desktop VoIP phones on the 7920, some capabilities, including phone books and other XML-based applications, are not available on this platform, a deficiency Cisco says will be corrected by the first quarter of next year.

The Cisco 7920 sports a variable-output power capability that lets administrators configure the phones' radios to transmit at levels from 1 mW to 100 mW (0-20 dBm). This feature is useful in dense-AP deployment scenarios found in many enterprise WLAN environments. Lower power output not only reduces the potential for interference, it also helps extend battery life between charges. SpectraLink is the only other vendor to support this variable-output power capability.

The phones communicate using SCCP protocol to manage sessions. You must use Cisco's Aironet wireless access points if you want to take advantage of prioritization of SCCP traffic. Cisco recommends setting up a separate wireless VLAN just for the wireless phones and assigning that VLAN higher priority. It's a smart approach that lets you maintain different security profiles for voice and data traffic. Aironet's Proxy Mobile IP solution is not supported by these devices, so though you can roam between APs on the same network smoothly, you won't be able to roam across IP subnets without dropping calls.

The 7920 phones are registered in the same way as Cisco's desktop phone is registerd. We entered key configuration information (MAC address and telephone extension) into CCM using a well-designed Web-based interface. We also let CCM autoregister phones, assigning extensions automatically. This worked very smoothly, not only for the Cisco 7920 phones, but for the SpectraLink SCCP phones as well.

Cisco is usually closemouthed about future developments, but the company shared its wireless VoIP product road map for the coming year. It's reassuring that Cisco is sensitive to some of its shortcomings, such as multibay chargers and push-to-talk support--or hoot and holler, as Cisco likes to call it. There are also plans to include support for WPA (Wi-Fi Protected Access) security, Layer 3 roaming, local language support, SIP and voice-activated dialing. XML support will allow for access to corporate phone books.