Can a Verizon and/or AT&T iphone 4s be unlocked to be used for a tmobile carrier?

Can a Verizon and/or AT&T iphone 4s be unlocked to be used for a tmobile carrier?

Verizon phone can't, AT&T one can.

Hi

Verizon can't use t-mobile network becasue verizon iPhone can't support gsm sim card
AT&T can use by all GSM Sim card around the world so you can use AT&T iPhone with T-Mobile Sim card
you can unlock your AT&T iPhone by AT&T unlocking solution provider they will provide you unlocking solution i hope this provider will help you a lot