I got my iPhone on Saturday and got it activated in about 45 minutes. Everything works great except for the texting. Brand new ATT account, and like the other users I can send to anyone and they get it just fine. Can't receive any except for ATT users. So I was on the phone with first Apple Tech support, did the usual reset, restore and then no change. Went to level 2 support and still couldn't fix the problems. Apple then sent me over to ATT support. 4 hours later of tech support they have it working, sort of
The only way they could get it working as of now is for the people to send a text message like this. Your phone # and then this,
ex: (XXX)
XXX-XXXX@mobile.mycingular.com as the "phone #" to send the text too. This did work! But when I try to reply instead of the usual phone # to reply to you now have that person's phone # plus the web address of their provider. Well, now I couldn't send the text back to this person. So I had to start a new text message with their phone #!
I'm sure not everyone is texting this way, so there must be something going on somewhere! I hope this helps for now.