Phones sometimes just need a break- turning them off and back on is all you need to do:
Sometimes dust can get between the SIM and the phone causing communication issues:
Your issue will be with either your SIM or your phone, find out which by trying your SIM in a different phone or a different SIM in your phone.
Our Geek Squad Agents are technology experts who are waiting to take your call or talk to you instore. They also have lots of technical advice for you online. Visit the Geek Squad website for more information.