If you purchased your device from T-Mobile, the SIM card is probably installed. If not, you must provide your phone's IMEI ...

An IMEI (International Mobile Equipment Identity) number is a unique identification number that is associated with a SIM card slot on smartphones and tablets. If there are dual-SIM slots in your ...

If the phone is stolen, you can call your network provider and ask them to blacklist the device with the IMEI number. This process will make the device useless to the thief even if the SIM is ...