No, not only AT&T, actually, almost 99% of Europe uses GSM and the rest uses CDMA(verizon, sprint, etc). However, while the innerwork of the 2 are different the result (as far as text and voice) is the same, one 3 seconds of signal will be more than enough to transmit the packets. the main difference is with cdma you cant browse the net while you talk and GSM allows you too. However, that is not a point of contention here.