>Perhaps this is different between providers? On the CDMA side (i.e. Verizon, Sprint), yes. On the GSM side (T-mobile and AT&T), if your phone is locked to a

>Perhaps this is different between providers? On the CDMA side (i.e. Verizon, Sprint), yes. On the GSM side (T-mobile and AT&T), if your phone is locked to a carrier it will still accept any SIM from that carrier and your carrier provided SIM will work on any GSM unlocked phone with compatible frequencies.