On Wednesday, T-Mobile and Comcast announced a partnership to combat the industry’s growing robocall problem. Starting today, the companies will begin authenticating calls made between their networks in order to verify for consumers when the caller is an actual human being.

Americans received over 26 billion unwanted robocalls last year, and after a few light pushes from federal agencies like the Federal Communications Commission, carriers are beginning to deploy an authentication system that’s meant to combat them, known as the SHAKEN/STIR protocol. T-Mobile and Comcast will begin using the protocol to authenticate calls made between the two networks on a handful of devices.

“Robocalls and spam calls are an industry-wide problem, and we’ve got to join forces to keep consumers protected. Today, we’re the first to cross industry lines to do just that,” said John Legere CEO of T-Mobile.

The SHAKEN/STIR protocol verifies authentic calls by using digital certificates that help determine where a call is actually being placed. If a real caller is identified, T-Mobile will display “Caller Verified” in the Caller ID. T-Mobile began verifying some calls within its own network in January, and this partnership will extend that to calls placed between T-Mobile customers and customers of Comcast’s home phone service.

The protocol will start rolling out to 10 devices, including the LG G8 ThinQ, the Samsung Galaxy Note 8 and Note 9, the Galaxy S8, S8 Plus, S9, S9 Plus, S10, S10E, and S10 Plus. T-Mobile says it will be available on the Galaxy Fold and the A6 soon and other devices across their networks in the coming weeks and months. Comcast customers will have to wait until “later this year” before they see the verification message.

“Fraudulent robocalls hurt everyone, so we want to give consumers more power to protect themselves,” Eric Schaefer, senior vice president at Comcast Cable, said. “Our engineers played a key role in developing this technology for the entire industry, and we are happy to work with T-Mobile to deliver another first in the fight against fraudulent robocalls.”

In March, AT&T announced its SHAKEN/STIR partnership with Comcast as well, but call verification between the two networks hasn’t started yet. T-Mobile said it would likely be partnering up with other carriers like AT&T and Verizon in the next few months in order to authenticate more calls between the networks.

The SHAKEN/STIR system does have some limitations. For now, it’s only capable of verifying that the person on the other line is a human. It cannot detect spam calls. That means the system will become far more useful as more networks implement it and allow it to authenticate calls across service providers.