Once you have debranded your 3-mobile phone you may have a few issues:
When debranding a 3-mobile phone if you still want to use a 3-mobile USIM in the phone and want to access their features, such as downloads, msn, etc, you'll have to have some Java certificates (I think, correct me if I'm wrong). It think the certificates are called "Authority 5" and "Authority 6". With these certs you'll be able to download games and applications from the 3-mobile wap site via your phone. I don't know where to get these certificates from and also don't know how to upload them, so if anyone knows, it would be much appreciated if you could tell us or point me to somewhere where it says how to :)
The sms delivery report options will not be present. To fix this problem I think you'll either have to edit the GDFS or edit the USIM. Again, if anyone has more info on this it would be very useful :)