Press Menu button u ll see apear on screen Apn no requiring
just select any operator and set defult apn
then press again Menu button u ll see again New apn no required then Just write manually which sim operator using the apn no just write this..
________________________________________________________________
turns off and Turns on the phone u ll see signing required then just sign in by ur Valid user/pass
_________________________________________________________________
Optional:-
If your G1 Google smartphone is not responding or is frozen, you may have to opt for a hard reset. Here