I have been emailed this from a Kogan Mobile User on how to enable iMessage/Facetime. This is needed (at the moment) as the default SMSC will not allow the iMessage activation message to go thru on the iPhone.
1. Disable iMessage under Settings/Messages
2. Dial *#5005*7672# and make a note of what the SMSC is set to at the moment
3. Dial **5005*7672*+61418706700# to set Telstra’s SMSC
4. Dial *#5005*7672# to make sure it changed.
5. Enable iMessage under Settings/Messages
6. Dial **5005*7672*thenumberyouwrotedowninstep2# (or you won’t be able to send)
6. Reboot phone (If needed)