Last year T-Mobile teamed up with AT&T to being offering cross-network call authentication using the STIR and SHAKEN standards, and now T-Mo is doing the same with another major carrier.

T-Mobile and US Cellular are now offering caller verification across networks. This means that when a T-Mobile customer calls someone on US Cellular, or vice versa, the carriers will validate the incoming call so you know that it’s actually coming from the number displayed on your caller ID. When a call is verified, you’ll see “Number Verified” on your screen.

T-Mo and US Cellular are doing this using the standards known as STIR (Secure Telephone Identity Revisited) and SHAKEN (Signature-based Handling of Asserted Information Using toKENs). These standards validate the handoff of calls between networks to verify to fight caller ID spoofing, which happens when a scammer hijacks a phone number to match the area code and three-digit prefix of the person they’re calling to make their call look seem legitimate.

This caller verification feature is part of Scam Shield, which T-Mobile launched earlier this year. It includes Scam ID and Scam Block free for both T-Mobile and Metro by T-Mobile customers.

Scam ID is free and automatic for all T-Mobile customers. To turn on Scam Block, you can download the Scam Shield app for Android or iOS, or dial #662# from your phone. You can also get free Caller ID using the Scam Shield app or by dialing #436# from your phone.

T-Mobile currently offers more than 120 devices that display “Number Verified” or “T-Mobile Verified” when a call is coming in.

Source: T-Mobile