Hey - We will need a bit more details on the issue in order to best assist. Have you tried restarting the tablet (it is necessary to do so for it to register to the network). Are have you tried in a different SIM and restarted the tablet again? Are you able to make and receive calls and send SMSs (data connection may be just off)? Please kindly comment below with the answers to the above and we will try and assist further.