Slate: Major U.S. Phone Companies Agree to Plan to Combat Endless Robocalls.
[1]https://slate.com/news-and-politics/2019/08/major-u-s-phone-companies-agree-t
o-plan-to-combat-endless-robocalls.html

References

   1. https://slate.com/news-and-politics/2019/08/major-u-s-phone-companies-agree-to-plan-to-combat-endless-robocalls.html