Mass.gov: “…The principles, announced today by a group attorneys general in partnership with AT&T, Bandwidth, CenturyLink, Charter, Comcast, Consolidated, Frontier, Sprint, T-Mobile, US Cellular, Verizon, and Windstream, will help service providers incorporate call-blocking technology, monitor their networks for robocall traffic, and cooperate with investigations that trace illegal robocalls…The principles announced today include:

• Offering free call blocking and labeling to customers.
• Implementing call authentication industry standards.
• Analyzing and monitoring network traffic for patterns consistent with robocalls.
• Investigating suspicious calls and calling patterns.
• Confirming the identity of commercial customers.
• Tracing illegal robocalls back to their source.
• Cooperating in traceback investigations, which track illegal robocalls across networks to determine the source.
• Communicating with state attorneys general to help identify scams and trends in illegal robocalling…”