Sign Up for Your Carrier’s Robocall Alert Service
Many companies, including Verizon, AT&T, T-Mobile, Sprint, and U.S. Cellular, have introduced services that alert you that an incoming robocall may be from a scammer or spammer. In some cases, such services are free, but for a few dollars more per month you can get a more robust version that can block the robocalls from ringing on your phone.

Download a Call-Blocking App
Instead of simply being alerted to incoming robocalls, a call-blocking app can intercept robocalls before they reach you, says Mahoney of Consumers Union. Among the providers are Nomorobo, which charges $2 per month for its service (there is no cost for landlines), and free apps such as Hiya, Mr. Number, RoboKiller, and YouMail.