galaxy s3 not registered on network t mobile

my galaxy s3 gets a ‘not registered on network’ error when i call.
it’s for tmobile and i have a tmobile sim.
how can i fix this?
Answer #1
Is there another SIM you could try the phone with? Or better still, take it down to your closest TMobile store
Answer #2
You should have a setting to select what network to connect to. Just look for network or something under settings.
Answer #3
You should have a setting to select what network to connect to. Just look for network or something under settings.
Go to
Settings > More Settings > Mobile Networks > Network Operators
Are you sure the phone is not locked to another provider ?