Then you have to contact the carrier/service provider you are wanting to use to get a SIM from them for that phone. If the phone is, however, locked to a different carrier/service provider, then you can't make any change until you get it unlocked.
Then you have to contact the carrier/service provider you are wanting to use to get a SIM from them for that phone. If the phone is, however, locked to a different carrier/service provider, then you can't make any change until you get it unlocked.