Android Question

I have a galaxy s5 that I an trying to use with the walmart family mobile plan. When I place the SIM in the phone and turn it on the phone says "no service" on the top but has the signal bars full. When trying to make a call I receive a message saying "not registered on network" and the call is ended. I have updated my APN settings to my providers specifications but still dose not work. Can someone help me resolve this issue thank you in advance
Yes the phone came from a friend who was running t mobile on it and the service I'm trying to run is powered by t mobile. If it wasn't compatible wouldn't it not even reconize the SIM? It don't tell me to unlock the phone or that the SIM is invalid it just says no service and when trying to place a call it says not registered on network
Sounds like the Sim has not been activated. When you check in settings-about phone, can you find you phone number listed and service active?