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Wireless carriers in sync on 911 tech

T-Mobile joins two other major carriers in a strategy to meet a federal mandate requiring them to pinpoint the location of a cell phone dialing 911.

Three U.S. wireless carriers are now stepping in unison with a technology strategy to meet a federal mandate requiring them to be able to locate cell phones that dial 911, newly filed federal records show.

This week T-Mobile, the last of the wireless carriers planning to use CPS's Enhanced Observed Time Difference (EOTD) software, decided to switch to another technology. AT&T Wireless switched late last year, and Cingular Wireless made the change earlier this year.

The Federal Communications Commission has required all U.S. carriers to meet a 2005 deadline giving emergency call centers the ability to locate 95 percent of all handsets dialing 9-1-1 within 50 meters (about 50 yards). The carriers also planned to sell new "Friend Finder" or other commercial services using the technology to help earn back some of the costs required to build the system.

The two-page T-Mobile filing with the Federal Communications Commission briefly lists reasons for its change, among them that the decisions by Cingular and AT&T Wireless would "draw vendor time and resources away" from the attention the CPS software needed to meet the accuracy requirements.

"This was not an easy decision," Robert A. Calaff, T-Mobile senior corporate counsel, wrote to the FCC.

"T-Mobile's decision reflects its recognition of the practical difficulties of being the only nationwide carrier (using the EOTD technology)," Calaff wrote.

The three carriers now plan to use a version of Time Difference of Arrival (TDOA), which determines a phone's position by measuring the time a call reaches "location measuring units" inside a cell phone network base station.

Carriers installing the technology need to add software into their networks only. EOTD, on the other hand, requires software in a network and in specially made handsets.

An AT&T Wireless executive speaking on condition of anonymity said EOTD wasn't accurate enough to meet the federal mandate. It could find a targeted cell phone within 100 yards, but "we were not seeing a path to 50 meters nearly as quickly," the executive said.

Other carriers, including Verizon Wireless and Sprint PCS, have chosen different methods that use a constellation of satellites.

Ashcroft said CPS will now focus on selling the Nortel Networks, Siemens and Ericsson network gear with its EOTD inside to carriers in Europe as well as Asia, where its being tested by Singapore Telecommunications (Singtel).

"Our U.S. market experience has been very valuable in the development of this technology," he said.

"The U.S. is just 5 percent of the worldwide market," said Colin Ashcroft, a spokesman for Cambridge Positioning Systems (CPS), the creator of EOTD. "There's 860 million other cell phones."