Do I cancel my old phone service before or after my number is transferred?

DO NOT CALL T-MOBILE TO CANCEL YOUR SERVICE. If you do this, you will lose your phone number. It will just go back into the pool of numbers to be assigned to accounts.

There is no need for you to communicate with T-Mobile at all about the switch. It will be done for you. When AT&T puts in the port request (the request to bring your number over to your new AT&T account), T-Mobile will automatically cancel your service and send you your final bill.

Equally short but more correct answer - neither.

As mentioned repeatedly above, you don't cancel your account, AT&T does it for you.

When you sign up for AT&T service via iTunes you will port your number over. The moment you start porting your number it will cancel your account with whatever service provider you have. I suggest if you still have question call an AT&T rep and they will be able to help you.

You don't need to contact T-Mobile.

AT&T will take care of the entire process for you. During your iPhone activation process with iTunes, there is a selection for porting a number from another provider. You enter your T-Mobile cell phone number and AT&T takes care of the rest. T-Mobile will mail you your final bill automatically so there is nothing else you need to do.

I used to be with T-Mobile, but I don't remember if there was anywhere on the website where you could look for that information. If you have been with them more than two years and haven't extended your contract during that time by buying a new phone or switching to some special rate plan, you probably are not in a contract. However, if you're not sure, just call the customer service number and ask them if you're in a contract or if you're month-to-month.

Also, I thought I saw a story recently about T-Mobile users being allowed to leave their contracts without penalty because of some kind of fee dispute...if you're still in a contract, you might want to see if there's any validity to that story.

Addendum: Never mind. It looks like the story I saw "recently" was actually in May. Chances are this no longer applies.

<edited by host >

Message was edited by: 4n6doc

If you have been with them for over 2 years but are recieving monthly bills for your service then that means you are still in a contract, but can cancel with absolutely cancel without a termination fee.

...but can cancel with absolutely cancel without a termination fee.

What does this mean?

Short answer: after.

4n6doc wrote:
Equally short but more correct answer - neither.

Agreed!

Slightly longer rule of thumb: not before (so the number doesn't float away).