AT & T and Comcast are partnering to authenticate calls made between the two networks, allowing customers to know when there is a real caller – not a spammer – on the phone. It will not cover all the calls that AT & T and Comcast customers receive, but it is a step in the right direction to fight the robcalls' scourge. SHAKEN / STIR (which means "safe handling of requested information using toKEN" and "Secure Telephony Identity Revisited"). The protocol allows users to understand when the call is actually placed on the display number indicated on the caller ID. AT & T and Comcast said they hope the system will work for its customers later this year. It's not clear how you can determine if the call is spam, but it is likely to show an identifier when you receive a call that is legal.
Currently, the system has some limitations. It can only be used to identify legitimate calls ̵