My bf has a Siemens SL 55 which was on contract on orange he now has a new phone and said i could use his one. Tried putting my sim in (virgin) and won't work. Does anyone know the unlocking code for this phone. Also, when he put another orange sim card in that didn't work either? ... Thanks

Get in touch with Dirk Diggler from this site, he has a web site which runs a service that unlocks mobile phones, apparently he has reasonable prices.

I think you need a cable to unlock Siemens phones. You can pick them up for a few quid but it's probably just as cheap to have Mr Diggler do it.