If you purchased your device from T-Mobile, the SIM card is probably installed. If not, you must provide your phone's IMEI number. The customer service rep may also ask for the ICCID number on ...

This means the phone won’t make/receive calls anymore or connect online via the cellular network, even with a new SIM card. The number also reveals loads of other details about a phone.

Changing carriers can be exciting. You might get to pick up a new phone, or maybe you want better coverage in your home area. Either way, you have to know how to get set up. Each carrier tackles ...