just did it as written in post #13 and it works... I did it by unlocking the SIM tray and keeping it pressed with finger until the moment login screen appeared - then let it go and it goes offline... phone will keep switching You to the "select network" screen, so go to settings -> internet connection -> int.conn OFF, then enter the credentials, put the SIM tray in, set int.conn. ON, and tap login...

EDIT: ... and don't forget to disable "logout on exit" in settings