AT&T has begun to shut off TDMA networks in select cities, notifying TDMA and GAIT users in those markets that they must upgrade their handsets to GSM models. Trial shutdowns have begun with small areas where TDMA and Analog networks are separated. If successful, AT&T plans to shut down larger zones, including whole states, this summer. Areas where analog and TDMA service share a network will not be shut down until after the analog sunset in February 2008, confirming previous statements from the AT&T. The company added that now 99% of all voice minutes are carried on its GSM network, up from 95% in March.