Solved! Go to Solution.
Fantastic news - I now have an iPhone 4 that works - after having my phone backed up and restored twice by o2 and again by apple, the problem was still there.
Enter Daniel (Guru) from the o2 shop in Norwich, he checked everything that the others had done but would not be beaten - everybody thought it was TU GO but it been deleted and made sure it was not on the system and all accounts removed - well it was TU GO he reloaded the app then removed the iPad, iPhone3, that was still attached to it even though the app had been deleted from all the devices. Opened the app and started again and made sure the "CALL FALLBACK MODE" is ticked. that was the problem.
Now the phone rings on the first ring not the 4th, 5th or even 6th ring.