My SD had full signal in the top notification bar but on the orange widget that shows wifi, battery and signal it had none.
3G was on notification bar and was green to show connected but I was not able to send a txt, recieve a call of open a broswer yet my girlfriends Samsung Galaxy SIII on same network could.
I went to orange today as yesturday almost no signal all day
They said there is no problem with the SD and that if it continues I should factory reset the phone and if it still continues then I should go back for replacement.
Thing is this issues is intermittent for me and has only happened twice since my contract started about 6 mounths ago.
Guess have to put up with it for another 18 months then get new phone.
Currently have: Orange San Diego, Orange San Francisco, Viewsonic 10S, Freelander PD10 3G "Monster phone"