Nobody likes fraudulent robocalls. That’s why we’re excited to announce that AT&T and Comcast have taken an important step forward to address the problem – an exchange of authenticated calls between two separate providers’ voice networks that is believed to be the nation’s first.

This milestone helps pave the way for AT&T and Comcast to begin offering authentication on calls between networks to customers later this year. Customers could soon start to see verified calls not only from callers using the same provider, but more importantly, from other participating providers.

The test used phones on the companies’ consumer networks – not in a lab or restricted to special equipment. It was conducted March 5, between AT&T Phone digital home service and Comcast’s Xfinity Voice home phone service.

The calls were successfully authenticated and verified using the SHAKEN/STIR protocol – believed to be an industry first for calls between separate providers.  AT&T and Comcast played key roles in developing and refining SHAKEN/STIR, which is an important tool in the broader effort to combat fraudulent robocalls.

SHAKEN/STIR verification lets consumers know that an incoming call is really coming from the number listed on the caller ID display. While authentication won’t solve the problem of unwanted robocalls by itself, it is a key step toward giving customers greater confidence and control over the calls they receive.

For example, a call that is illegally “spoofed” – or shows a faked number – will fail the SHAKEN/STIR Caller ID verification and will not be marked as verified. By contrast, verification will confirm that a call is really coming from the identified number or entity.

Over the coming months, major service providers will be conducting similar tests with each other’s systems, verifying that their SHAKEN/STIR implementations are compatible.

To learn more about industry and government efforts against illegal and unwanted robocalls, see a recent blog post from USTelecom here.

AT&T and Comcast jointly chair the working group developing the technical standards for STIR/SHAKEN. AT&T holds the chairmanship of the industry board overseeing the SHAKEN/STIR effort and Comcast is a member of that board.

In addition to its leadership role in developing and implementing SHAKEN/STIR, Comcast’s Xfinity Voice works with Nomorobo to make robocall blocking technology available to the vast majority of Xfinity Voice customers. Customers can sign up to use Nomorobo service using their Xfinity username and password. Detailed instructions for using Nomorobo with Xfinity Voice are available here.