T-Mobile filed at the FCC a list of...

T-Mobile filed at the FCC a list of counties, or parts of counties, it serves in which it can’t use triangulation to locate callers to 911. All made the list “because of insufficient quantity, density, and/or geometry of cell sites in those areas to support network-based triangulation,” T-Mobile said. The nine-page list (http://bit.ly/1beRGhZ) adds 62 counties to the previous list from 2011. The FCC’s 911 location-accuracy rules require carriers to identify callers with a defined level of accuracy on a county-by-county basis, but provide exceptions where dense forestation or the lack of triangulation mean those levels can’t be reached.