I'm using an S3 on T-mobile and I can send MMS picture messages to all my contacts except one. When I send to this one contact the message 'service not activated on network' appears briefly and then the mesage 'Failed MMS' appears underneath the MMS message.

The affected contact, who is using an iPhone on Three, can send MMS messages to me and can receive them from anyone else, just not from me.

I have tried rebooting, removing and replacing the SIM card, clearing cache, but the problem persists with this one contact.

Has anyone seen this before or have any ideas to resolve?

Thanks

Phil