Several AT&T users have reported an issue in which incoming text messages are never received by the iPhone 3G. The problem is most common with accounts that have been ported from other carriers like Verizon and T-Mobile.
As described by a poster to the AT&T discussion forums:
"Got the iPhone on July 11th, ported from T-Mobile on the 14th. I have been having issues with getting texts ever since. I have called customer support seven times and finally got someone to open a trouble ticket with the inter-carrier text message service provider. We'll see what comes of it."
AT&T support representatives are telling customers that the issue lies with VeriSign, which maintains the aforementioned inter-carrier database. Another poster writes:
"The lady on the phone said that they have received many calls regarding the issue and after an exhaustive period of research, have determined the problem to be on the Verizon side. Furthermore, VeriSign has indicated that the problem exists due to database discrepancies between Sybase 365 and Verizon. She urged me to have the Verizon customer(s) in question call and start a ticket with Verizon. She indicated that ATTT would do anything they could to help, but at this point it is a Verizon problem and needs to be addressed on the Verizon end."
Users experiencing this issue generally have no issues sending text messages.
In some cases, calling AT&T technical support and asking the representative to reset an account's routing number can resolve this issue.