Hello, I have a Sony Ericsson Xperia Ray which was previously locked to Orange, but I got it unlocked so that I could use my GiffGaff SIM with it. At first I had a few problems setting it up, but then found a app called -Tweaker- which helped set up the internet, and APN. Everything worked fine for about 3 days, but now I can't make calls or send msgs, there is an error icon -Selected network 02 unavailable-. The internet works fine though, and I'm not on Wifi. It also now says -Emergency calls only- ! I've checked my postcode on the 02 website and it's fine, says there are no problems. I have enough credit. I put my SIM into an old phone, and lots of messages came through, and I was able to make calls. So it must be the phone, not the network? Any ideas? I've already asked on GiffGaff forums, but no luck. Help!