What do I need to know before buying an unlocked GSM phone?

[Dennis Matveyev]

I am now off my contract with AT&T. My old phone broke so I went out and purchased a new Note 5 via AT&T.

Now I am thinking -- it's a $840 phone that is locked to AT&T. Will I do better to instead return the phone to AT&T and get something that is GSM unlocked instead? Since I'm gonna pay full price anyway, I might possibly have use for it overseas if I ever go somewhere outside of US. Although I am not sure how much of a benefit it is really.

If I choose to go with GSM, can I just buy something on Ebay like "Samsung Galaxy Note 5 64GB SM-N920i Factory Unlocked". Can I hope that AT&T as my current carrier will give me a SIM card that works? Will I experience anything unexpected?

 

[B. Diddy]

The most important thing is to make sure the unlocked phone supports AT&T's network bands: https://en.wikipedia.org/wiki/Cellular_frequencies. Do a Google search for the exact model number you're considering, and make sure the network bands it supports overlap with AT&T's.

Also, be very cautious about buying a used phone from anyone else--make sure they remove their Google and Samsung accounts from the phone prior to doing a factory reset. Otherwise, after the reset, you'll have to enter their account information to proceed (this is Factory Reset Protection).

You should have no problems getting a SIM card from AT&T to pop into the new phone. T-Mobile charges about $10, but I think AT&T doesn't charge anything.