Anybody had problems using an old BT Cellnet SIM card in a modern phone nokia 3100. The phone recognises the network. o2 OK I can phone to the 3100 with the old sim card and it connects OK. But when I try to phone out I get the message "call not allowed". I have gone thro all the menus with a fine toothcomb to no avail. The phone is locked as it wont recognise an orange sim card but works perfectly with a mate's newish o2 card so no problem there. I have come to the conclusion that the phone lock whether network,provider or sim is not allowing me to connect to the network as a" cellnet" o2 user rather than a "o2" o2 user. This really pisses me off since I bought an o2 phone to allow me to continue to use my old number/simcard call credit. Having spent time and money with "customer services" what a joke and my local o2 shop who knew nothing about the technology they were dealing with I am at a loss. I could get the phone unlocked professionally but I still dont know if that would work. I have tried various unlock code software utilities and tried 3 times to unlock the phone myself but I am only allowed 5 tries before the phone locks permanently. Any comms tech guys come across this problem and did you solve it????