Does unlocking a phone disable my present AT&T service?

[Murgatroyd]

My contract with AT&T expires in December. I probably will use T-Mobile afterwards. If I unlock the phone now with a backup and restore from iTunes, will my phone remain operable with AT&T for the remaining two months?

I can now change SIM cards anytime in the future is all I've changed inside the gizzards of the iPhone 5 after unlocking? Correct?

T'anks.

 

[617aircav]

No. It will be fine.

 

[Murgatroyd]

That's a big ten-four. Yes,sir.