One, mobile phone to a good signal or network coverage rate of a high place
Your Samsung phone may be having problems with poor signal or network coverage. The problem with the phone may be caused by poor signal coverage. Try to move from the current location to the outside, preferably to the open space.
Second, shutdown and restart the phone
If it is a system failure, then turn off the phone and then boot to solve the problem.
Third, manually choose mobile phone Network
1. Click "Application" on the standby desktop.
2. Click "Set".
3. Click "Connect" and select "More Networks".
4. Click on "Mobile network".
5. Click on "Network Operator".
6. Click "Search Network".
when you are done, wait until the operator list is displayed and click on your SIM card's corresponding network operator.
most of the existing handsets support multiple frequencies used for communication. If your device still does not receive a signal, you can try to turn off your 3G service.
If none of these measures will solve your problem,