Ive been in touch with Three, my provider who have guided me through every last step to try and resolve this. I have thus far reset wireless settings, checked my carrier settings, done a total restore. Nothing is working. I have been given such a load of excuses from Three, such as mast congestion, fixing a problem in my area etc. There are no problems as a check shows good strong signal in my area. I have a feeling that the lastest update isn't compatible with the phone. Whats going on? Please help as this has been going on for 3 weeks.
Try using someone elses sim card. If that works you know you sim card is faulty. I have had 3 days trying to sort my new sim card with the same problem. Tried my grandsons sim in it and it worked fine.
So basically they sent me a new sim card and never validated it when I phoned them. still waiting.