T-Mobile, Comcast Kill Cross-Network Robocalls

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T-Mobile and Comcast have broken new ground as the first carriers to form a partnership to offer cross-network protection against robocalls via STIR/SHAKEN standards, the service providers announced today. The former of the two companies also revealed that its own internal anti-robocall feature, Caller Verified, works with no fewer than ten of the smartphones it offers.

The announcement means that customers on either network will need to worry about fewer spoofed, spam, or malicious calls since those made to or from T-Mobile and Comcast’s Xfinity Voice home phone service will be vetted. On T-mobile’s side of the equation, protections are available now with Comcast set to implement the change at some unspecified point later this year.

T-Mobile’s Caller Verified informed users when an incoming call has been verified for authenticity and has already been available on the Samsung Galaxy Note 9 since January. As of the announcement, that will be rolling out via a software update to customers with an LG G8 ThinQ or Samsung’s Galaxy Note8, Galaxy S8, Galaxy S8+, Galaxy S9, Galaxy S9+, Galaxy S10, Galaxy S10e, or Galaxy S10+ handset.


The lowdown on STIR/SHAKEN

T-Mobile and other carriers have been working to implement new standards since last year, following the FCC’s decision to call out and threaten action against providers who do not prevent robocalls. Caller Verified was among T-Mobile’s first steps toward meeting the required changes.

Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted Information Using toKENs (SHAKEN), at their most basic, are two sides of the same solution. They are intended to help a network both mark and verify phone calls, checking the origin against registries for authenticity.


That doesn’t just rely on a phone number in a database either. The numbers are tied to other device identification metrics, ensuring that a phone call can’t be faked via the same number from somewhere else on a different device. In short, it takes network protection services offered in some smartphone applications and joins them at a network level with additional bolstering to improve consumer safety with regard to call-based scams and related activity.

Where is the rest of the industry on this?

Verizon is following almost in lock-step with T-Mobile in terms of protecting its own consumers via a dedicated phone-based feature called Call Filter. As with the similar offerings from Sprint and AT&T, that’s free in a limited fashion for customers with improved paid versions available that are more comprehensive.


None of the big four carriers in the US are currently protected in any way that could be called comprehensive, however, and that is shown by the various companies’ primary reliance on apps instead of cross-network protections. AT&T, in particular, suffered the embarrassment of its own CEO receiving a robocall while on stage at a DC event in late March.

T-Mobile and Comcast’s claimed “first” in implementing a cross-network verification against those calls may seem somewhat overhyped since it only works between home phone service and a single wireless carrier. But, with as many as 26.3 billion robocalls placed over the course of 2018, it could prove instrumental in kickstarting progress toward ending a widespread problem that has now escalated out of control.