See the full version of manual..
On page #30,
If a customer decides to insert their iPhone SIM card into another AT&T device they will have the following experience:
- Visual Voicemail will not be available, however regular voicemail will be accseeible by pressing "1" to hear messages.
On page #31
- MediaNet will be used to access the internet. MMS and IM messages are included in the customer's iPhone data plan.
- bla bla bla
this is about using iPhone SIM card to non-iPhone device.
iPhone doesn't support MMS and IM.
Wake up guys!