Whilst visiting the UK recently I swapped my SIM for a UK SIM and everything worked fine. I added a contact to my phone and messaged with no problem. However, now I am back in Australia and have swapped the UK SIM back to my Australian SIM the SMS no longer sends to my UK friend. (I changed the contact to contain + and country code). No problems with SMSing anyone else, just this one number. I've tried deleting the contact and conversation then creating the contact again but still it won't send. Does anyone have any ideas what I can do? Thanks.