do at&t phones work on verizon network?
GSM vs CDMA Carriers operate under one of two types of networks: CDMA or GSM. Out of the four biggest carriers with their own network, AT&T and T-Mobile run on GSM, while Sprint and Verizon Wireless use CDMA. ... In general, an unlocked GSM phone from AT&T and T-Mobile will work on each other's networks.