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T‑Mobile Completes STIR/SHAKEN with ALL Major Carriers to Help Protect Customers from Scams and Spam

T-Mobile Media Release | March 25, 2021

  • What’s the news:  T-Mobile is the first US wireless provider to work with all other major networks – including those with slower 5G networks (which is all of them) – to implement STIR/SHAKEN to fight number spoofing and further protect customers from scammers. With these partnerships, T-Mobile now authenticates calls with wireless and network providers that collectively represent around 98% of wireless customers in the U.S.
  • Why it matters:  Scam calls are returning to pre-pandemic levels as scammers return to call centers across the globe. T-Mobile leads the industry in protecting customers from scam and unwanted robocalls, but wireless companies must work together to authenticate calls coming across networks and help stop these scammers in their tracks.
  • Who it’s for:  Anyone receiving or sending calls on the T-Mobile network.

Bellevue, Washington — March 25, 2021 — Scamming just got a LOT harder for scammers. T-Mobile (NASDAQ: TMUS) today announced the next milestone in its leading Scam Shield Un-carrier move to protect customers from invasive scams and unwanted robocalls. T-Mobile is now working with Spectrum Voice from Charter Communications, effectively partnering with ALL major networks in the US to deliver number verification to customers. With this news, the Un-carrier is the first in the wireless industry to implement STIR/SHAKEN with all major US network providers, well ahead of the June 2021 deadline set by the FCC. T-Mobile customers can rest assured that when a call comes in from any of the major carriers, or any of several other smaller network providers, to T-Mobile’s network (or vice versa), the companies will be able authenticate it’s coming from the phone number displayed in Caller ID and has not been spoofed. This makes Caller ID even stronger in the fight against scam and robocalls, and with Scam Shield, all T-Mobile, Metro by T-Mobile and Sprint brand individuals, families and small business get free Caller ID — so for the millions of businesses and people not your contacts, if we know who’s calling, you’ll know who is calling.   

“T-Mobile was first to implement number verification in 2019 because protecting customers against scammers and spammers is one of the most important things we can do as an industry,” said Mike Sievert, CEO T-Mobile. “To date, T-Mobile has protected over 80 million customers from more than 33 billion suspect calls – and counting. With the combination of Number Verification, free Caller ID and the scam blocking tools in Scam Shield, and by working with network providers of all sizes, we are providing the industry’s most comprehensive scam and spam protection for free to all our customers and working every day to make scammers jobs impossible.”

Last summer, T-Mobile launched: Scam Shield, a comprehensive and state-of-the-art set of tools to protect customers against scams and unwanted robocalls. With Scam Shield, T-Mobile and Metro by T-Mobile customers get automatic and free scam call warnings, the ability to block scam calls completely with Scam Block, and free Caller ID. Scam Shield leverages the power of the entire network to update constantly against the latest attacks and is free to all T-Mobile and Metro by T-Mobile customers. And research shows that T-Mobile’s network is 30% better at detecting scam calls than other major networks. And, Sprint brand customers get free identification and blocking in the upgraded free Call Screener app, previously $2.99 per line per month.

Every day T-Mobile is exchanging over 237 million calls verified by STIR/SHAKEN. T-Mobile has led the industry in implementing STIR/SHAKEN standards since announcing readiness in 2018, thanks to its ability to quickly implement new technologies on its network.  The Un-carrier was first to implement STIR/SHAKEN and protect customers against spoofing in January 2019. Now with fifteen cross-network partnerships and all major carriers working with T-Mobile, even the major carriers with smaller 5G networks (which is all of them), the company is first to deliver industry-wide STIR/SHAKEN protection for its customers.

Number verification is one key element in providing customers better ability to make decisions on which calls to answer and greater peace of mind that calls are not being spoofed. However, network companies must also have tools that identify threatening scam calls and provide customers the control to stop them. With free Caller ID for customers, and Number Verification broadly implemented, the Un-carrier is now providing customers with the best ability to decide which calls to answer…or block completely.

T-Mobile currently provides STIR/SHAKEN implementations with AT&T, Comcast, Spectrum Voice from Charter Communications, UScellular, and Verizon Wireless as well as Altice USA, Bandwidth, Brightlink, Clear Rate, Google Fi, Inteliquent, Intrado, Magicjack, Peerless, and Twilio.

For more information on all the ways T-Mobile is protecting customers, including capable handsets, visit  For Metro by T-Mobile customers, more information is available, including the list of over 126 capable handsets at The STIR/SHAKEN acronym stands for Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted Information Using toKENs (SHAKEN).  

Capable device required for some features.  Opensignal Awards T-Mobile as America’s Fastest 5G network – USA: 5G User Experience Report January 2021, based on independent analysis of average speeds from mobile measurements recorded during the period September 16 – December 14, 2020 © 2021 Opensignal Limited. Coverage not available in some areas. Some uses may require certain plan or feature; see

About T-Mobile
T-Mobile U.S. Inc. (NASDAQ: TMUS) is America’s supercharged Un-carrier, delivering an advanced 4G LTE and transformative nationwide 5G network that will offer reliable connectivity for all. T-Mobile’s customers benefit from its unmatched combination of value and quality, unwavering obsession with offering them the best possible service experience and undisputable drive for disruption that creates competition and innovation in wireless and beyond. Based in Bellevue, Wash., T-Mobile provides services through its subsidiaries and operates its flagship brands, T-Mobile, Metro by T-Mobile and Sprint. For more information please visit:

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