PIERRE, S.D. — Attorneys general representing all 50 states, plus the District of Columbia, have partnered with 11 phone companies in an attempt to crack down on robocalls.

According to a Thursday, Aug. 22, news release from South Dakota Attorney General Jason Ravnsborg's office, the agreement lays out eight principles for phone providers to follow in order to help attorneys general investigate and prosecute perpetrators, and prevent robocalls from happening in the first place.

The principles range from offering free call blocking and labeling to confirming the identity of commercial callers to investigating suspicious call patterns and more.

Henning Schulzrinne, a professor at Columbia University's Data Science Institute, said in Thursday's release that the principles "offer a comprehensive set of best practices that recognizes that no single action or technology is sufficient to curb the scourge of illegal and unwanted robocalls."

Ravnsborg said in the release that he is "encouraged by the cooperation and willingness of these telephone companies to assist in preventing illegal robocalls."

"Illegal robocalls continue to harass, annoy, and scam the people of South Dakota and this is a significant step in the right direction," he added.

The coalition includes AT&T, Bandwidth, CenturyLink, Charter, Comcast, Consolidated, Frontier, Sprint, T-Mobile, Verizon and Windstream.

Attorneys General Ravnsborg, R-S.D., Wayne Stenehjem, R-N.D., Keith Ellison, D-Minn., and Joshua Kaul, D.-Wis., signed onto the agreement.