Those who visited AT&T's Web site Wednesday to pre-order the device were greeted with the stark message: "Pre-orders for iPhone temporarily suspended."
Apple's Web site, however, for pre-orders of its popular phone appeared to be up and running, despite a deluge on Tuesday and slowness in getting through to the site. The phone goes on sale in AT&T and Apple retail stores on June 24.
AT&T said late Tuesday that it was looking into problems that resulted in "customers inadvertently seeing the wrong account information during the iPhone 4 purchasing process," after reports by some who were placing orders that they were seeing the data of other AT&T customers. In some cases, AT&T's systems took customer data without completing the orders.
"We have been unable to replicate the issue, but the information displayed did not include call-detail records, Social Security numbers or credit card information," AT&T said.
Any release of personal information is added aggravation for the carrier, as well as a concern to consumers. Last week, AT&T apologized for a security breach that enabled hackers to obtain 114,000 e-mail addresses of Apple iPad 3G customers, including many government and military officials. The FBI said it is investigating.
AT&T is the exclusive carrier of the iPhone in the United States. The new phone, which includes video calling between iPhone 4 users, costs $299 for a 32-gigabyte model with a two-year AT&T contract, and $199 for a 16 GB model.