Can you describe the problem you are having to us?

 

I have the same problem. The problem is not with your phone but with your carrier's network. In my case it is with Sprint. Just call your carrier's tech support again and describe your problem "again" Don't forgt to ask for a credit on your bill. Sprint gives me 25% of my bill every month for being thier network test dummy.

 

Since you have the same problem and the OP never stated what his problem was, can you inform us so we can try to help.

 

I have the same issue with GS3 on Wind. When the phone is on standby for extended period of time it drops connection with the tower for incoming calls and sms. People are not able to call in, they get "user unavailable" message. Everything else in the phone works: Internet, emails, outgoing calls. Once you place and outgoing call or send sms, or switch to an air-plane mode and back, phone is able to receive incoming calls.
It's happening in multiple locations in the area with a full network coverage.
Any ideas on the issue?

 

Do you use a case for your phone and if so what kind?

 

I do. a leather sleeve.

 

Got a call from Wind support that finally this became a known issue to them and they are working on a software solution. This affects some of the GS3 phones on Wind mobile network. Could take several weeks to resolve.