Can I use an unlocked AT&T iPhone with T-Mobile?

Question

I'm finally fed up with AT&T's exorbitant cost and ready to switch to T-Mobile.

I'm well past my contract obligation and have maintained my iPhone 5 in near pristine condition.

Can I have this phone unlocked and use it with another provider?

Answer 1

AT&T and T-Mobile both use GSM networks.

So yes, you will be able to use your iPhone with T-Mobile.

Answer 2

The technical issue with the 5 is that the AT&T models made in the first few months after release didn't support the 700Mhz band used by T-Mobile. You have to look at the serial number to know if your phone supports it. The details are in a tech note on Apple's site.

Your phone will still work even w/o 700Mhz support but, as noted, in some areas it will get E or 3G instead of LTE speeds. The practical effect all depends on where you use it.