If you can't make a call or if you see an error message that your phone's SIM card is not working, there are several ways to troubleshoot the problem. Ther error ...

Once you’ve activated your iPhone with your carrier, it should continue to work on the cellular network without any problems as long as you’re within range of a tower. Nevertheless, the vagaries of ...

A SIM card, or subscriber identity module, is a small card in your cellphone that connects you to the network. Your SIM card contains your phone number, and lets you make phone calls, send text ...