I've just bought what was originally an orange phone off ebay, and the guy who I bought it off had it unlocked so I could use it on O2. Now I've just spent pretty much most of the day deleting as many orange settings as I can find (using my o2 contract sim in the phone) and ringing people works, standard texts work, but GPRS & MMS dont.
I've visited the o2 webpage and downloaded and installed the settings to the phone, but whenever I try to use GPRS or send an MMS with or without a picture the 'G' Just flashes in the top right for a while (trying to send) and then the mms is bounced back to the outbox, where it waits to try again.