I live in a bit of a fringe coverage area but in one room of our house my phone indicates full or almost full reception, so usually when I'm home I leave my phone in that spot. Sometimes I'll notice that my phone has been quiet for a while and when I check it it's still indicating full reception, but when I go to make a phone call I get the "Not Registered on Network" message on the screen. I then have to turn Airplane mode on then off again to get the phone working again. Is this likely to be a network fault or a handset fault? The S3 is a 2 Degrees supplied one and I'm with Vodafone... Could this also be a problem?