T-Mobile branded phones operating on the T-Mobile network may only use T-Mobile SIM cards. To use a T-Mobile branded phone on another wireless carrier's network with a non-T-Mobile SIM card, you must first request a "SIM Unlock" code from T-Mobile. Conversely, if you have a phone from another North American wireless carrier, you may need to request a "SIM Unlock" code from that carrier before being able to use a T-Mobile SIM card on the T-Mobile network. * SIM Unlock Codes will only be provided after your account has been active for 90 days. Only one unlock code may be provided per customer every 90 days.