Updated with statements from T-Mobile, Verizon, Sprint and AT&T. Updated at 10:45 p.m.
AT&T reports that wireless and wireline service has been restored for all customers in parts of the Southeast affected by a hardware-related network issues.
AT&T, Verizon, Sprint and T-Mobile customers across the Southeast suffered hours of outages from early Tuesday afternoon and into the evening.
The outages were concentrated in Kentucky, Tennessee, Alabama and North Georgia, though each carrier's outage footprint differed slightly from the others.
In previous wireless service outages of this magnitude affecting multiple carriers, the culprit has been carriers' shared backhaul architecture, which ties the cellular networks together and in some cases is operated by a third party.
Sprint said the issue appeared to be caused by a "local exchange provider," and that the company's network team Tuesday night was working with the provider to restore service.
"Local exchange provider" is an industry term to denote a local telephone company. However, it remains unclear how an outage at a single telephone company could take down service for all major carriers across a major swath of the U.S., and a handful of short statements released by carriers on Tuesday evening did little to shed light on the cause of the massive outage.
DownDetector.com, which tracks outages at the major cellphone carriers, began tracking a huge uptick in outages shortly before 4 p.m., though the site became unavailable later in the evening.
AT&T spokesperson Cathy Lewandowski said the company was working to get service up and running.
"Some customers across parts of the Southeast are experiencing wireline and wireless service issues," Lewandowski said Tuesday afternoon. "We are investigating the cause and working as quickly as possible to restore service."
Wireless phone connections resumed around 8 p.m., for most AT&T phone users in Chattanooga.
On Twitter, T-Mobile's help group said its engineering team was aware of issues in Alabama and Kentucky and had "boots on the ground" working to get it resolved. In another tweet, the carrier suggested that a server issue had led to the outage.
Verizon said it was working with vendor partners to resolve the issue quickly. One Verizon spokesperson told the Middlesboro Daily News that the outage could last up to 24 hours.
Contact staff writer Ellis Smith at email@example.com or 423-757-6315.