BISMARCK — A coalition of 51 attorneys general has reached an agreement with 12 national telephone companies to help protect customers from illegal robocalls, North Dakota Attorney General Wayne Stenehjem said Thursday, Aug. 22.

The agreement calls for the phone companies to take immediate steps to help protect customers. It also will make it easier for authorities to locate, investigate and prosecute, according to Stenehjem.

The participating phone companies have agreed to implement call-blocking technology at no cost to customers, monitor their networks for robocall traffic and utilize technology to ensure that calls to customers are coming from a legitimate source. They also will investigate suspicious callers, notify authorities and help trace the origins of illegal robocalls.

“These telephone companies are in a better position than anyone to know when their users are making thousands upon thousands of calls, and to realize when these entities are nothing but scammers,” Stenehjem said. “Besides the sheer volume of these illegal calls, our biggest challenge has been locating the source of the calls."

The participating telephone companies are AT&T, Bandwidth, CenturyLink, Charter, Comcast, Consolidated, Frontier, Sprint, T-Mobile, US Cellular, Verizon and Windstream.