If anyone can help with this....

[V8Guzzler]

Ok, let's say you have a new mobile phone and you have decided to move from vodafone to O2 and transfer your number. Your sat at the airport waiting for the transfer to happen, but it doesn't actually take place until you arrive to your overseas destination. You turn your phone on with your new O2 sim card in... Will it work?

 

[NHN]

If O2 have enabled roaming on your sim then should do yes, but you must advise O2 you want roaming, although most turn on by default & make sure your data is disabled abroad or it may leave you with a massive bill when back as some phones connect to the net unknowingly to most joe blogg users, unless you have a specific contract with specified international data rates you're happy with.

 

[V8Guzzler]

For the record... It doesn't work...

 

[NHN]

Have you verified with O2 roaming is enabled?

It should automatically pickup a local network O2 has contract with & handshake back home & then should get sim updates to allow usage & features.

Strange as never had issues myself.