AT&T's wireless data networks in the Southeast and Midwest U.S. are down, causing BlackBerry and iPhone users to be without data services.

The EDGE (Enhanced Data Rates for GSM Evolution) and UMTS (Universal Mobile Telecommunications System) services in those regions began having problems around 6:30 a.m. EST this morning, said Mark Siegel, an AT&T spokesman. Voice calling has not been affected, but people trying to use wireless data services might have "difficulty," he said.

Several users of a BlackBerry newsgroup have reported being unable to receive data to their handsets. A systems administrator in Kansas reports that BlackBerry devices there are displaying a message that says "data connection refused."

AT&T is still looking into what exactly caused the failure, but technicians have found a solution to the problem and expect the service to be restored by around 3:30 p.m. EST, Siegel said.

The iPhone runs on the EDGE network, so users of the phones, as well as any other mobile device that receives data from either of the networks, will have problems using data services.

In early 2007, Research In Motion implemented a software upgrade that caused its systems to crash, resulting in a BlackBerry service outage that started in the evening and lasted through the night. This time, the problem appears to be with AT&T's network and not with RIM's infrastructure.

The IDG News Service is a Network World affiliate.