Wireless requirements on financial trading floors are changing, as discussed in the last newsletter.\u00a0 Mobility requirements at the Chicago Board of Trade aren't limited to data, though.The exchange is also enhancing its wireless voice network to accommodate the larger density of traders on its financial and agricultural trading floors.CBOT is augmenting its existing Ascom Wireless Freeset stand-alone wireless phone system with\u00a0a Spectralink Link Wireless Telephone System, which essentially provides "cordless extensions" to the exchange's new TDM-based Nortel Networks PBX."Use of wireless on the trading floor has been steadily growing," explains Ethel Laughlin, vice president of telecommunications. "We overloaded the Freeset system's frequency [1930 MHz]. Calls were cutting out, and connections were being dropped."So CBOT has shifted nearly 100 users to the Spectralink network, which operates at 900 MHz, thus avoiding interference with Freeset.\u00a0 CBOT has installed 64 Spectralink base stations beneath its 45,000-square-foot trading floor.CBOT supports about 640 wireless phones "in a relatively tight space," Laughlin says. Users can four-digit dial to any other phone in system, and trading group conference calls take place among local wireless phones, trading booths, and outside phones.The Freeset system is encrypted, and voice signals in the Spectralink system hop frequencies about 100 times a second. So both voice systems offer strong security measures.Why not merge voice conversations onto CBOT's 802.11b\/802.11a wireless LAN? The exchange doesn't consider wired or wireless VoIP to be robust enough yet for the stringent quality demands at CBOT, says Laughlin, who has tested the technology."It's not ready for prime time for our users," Laughlin says. "The complaints we got were about inconsistent service. Immediacy of dialtone is primary on the trading floor. Traders want to get orders from outside the building and enter them immediately."Cellular also wasn't an option. Aside from being cost-prohibitive, "you'd just run out of spectrum too fast," Laughlin observes.And what about the perpetual battery-life issue of wireless phones for traders who need phone service eight hours per day?Rick Skrypek, a wireless technician at CBOT, says the Ascom devices support 8 hours of battery time. Spectralink supports about 4 hours of use and 80 hours standby time."We issue two batteries to users, who can swap a battery within 30 seconds without dropping a call," Skrypek explains.