"Spam Likely" vs. a verified caller: what STIR/SHAKEN and carrier call blocking really tell you

A "scam likely" or "spam" label is your phone company's guess, based on call analytics, that a call is unwanted. A checkmark or "verified" badge means only that the number was authenticated and probably isn't spoofed. Neither tells you who's calling or whether they're honest. The FCC itself warns that people may mistakenly read a checkmark as an assurance that a call isn't a scam (FCC, October 2025).

Here's what each signal actually means and how to use your carrier's tools without missing calls you want.

What is STIR/SHAKEN?

STIR/SHAKEN is a caller ID authentication framework: a set of technical standards that let carriers "sign" and verify caller ID information on calls carried over Internet Protocol (IP) networks. STIR stands for Secure Telephone Identity Revisited and SHAKEN for Signature-based Handling of Asserted Information Using toKENs (FCC).

In practice, the originating carrier signs the call. Your carrier checks that signature, which lets it confirm the call really comes from the number shown on your caller ID.

Key dates and rules from the FCC:

• In 2020 the FCC required voice service providers to implement STIR/SHAKEN in the IP parts of their networks by June 30, 2021.
• The requirement has since been extended to most providers, including gateway providers (US-based providers that receive calls directly from foreign providers) and certain intermediate providers.
• Because STIR/SHAKEN works only on IP networks, providers still using older technology must either upgrade to IP or work on a non-IP authentication solution.
• Every provider must file in the Robocall Mitigation Database about its anti-robocall efforts.

What does a checkmark or "verified" badge mean?

When a call gets the highest level of authentication (an "A-level attestation"), your carrier may pass that on to your phone. Depending on your handset and operating system, the FCC says, you might see something like a green checkmark (FCC FNPRM).

What it does not mean:

1. It doesn't tell you who is calling. The FCC notes that STIR/SHAKEN can help you spot a spoofed number, "but it does not let them know who is calling."
2. It doesn't mean the call is legal or safe. A real, unspoofed number can still belong to a scammer.
3. A missing badge doesn't prove spoofing. Calls with lower attestation levels aren't necessarily spoofed, and some networks still can't carry the signature.

In October 2025, the FCC proposed requiring carriers to show verified caller name information whenever they show that a number is unlikely to be spoofed. It also proposed marking calls that originate outside the United States. These were proposals in a Further Notice of Proposed Rulemaking. Check the FCC for their current status.

What does "Spam Likely" or "Scam Likely" mean?

That's call labeling, which is separate from authentication. The FCC says some companies offer labeling that displays categories such as "spam" or "scam likely" on caller ID, to help you decide which calls to answer (FCC). Carriers and their analytics partners base these labels on suspicious calling patterns, and the FCC says STIR/SHAKEN information also supports their blocking and labeling decisions.

Because labels come from analytics, they can be wrong both ways:

• False positives: the FCC acknowledges legitimate callers sometimes get blocked or labeled when their calling pattern resembles robocalling.
• Missed scams: a scam call can arrive with no label at all.

What can my phone company block without asking me?

Under FCC rules, voice providers may block these calls without your consent (FCC):

1. Calls from unassigned, unallocated or invalid numbers.
2. Calls from numbers on the Do Not Originate list.

Providers may also block calls they consider unwanted based on analyzing call data, but you must be able to opt out of that type of blocking. Companies can enroll you automatically, and depending on your carrier, a blocked call may go to voicemail, ring once, or not show up at all.

How do I turn on call blocking?

1. Check your carrier's tools. The FCC's call blocking page has step-by-step guides for AT&T, T-Mobile and Verizon.
2. Check your phone's built-in settings. The same page has guides for Android and iPhone. The FCC says to follow both your device guide and your carrier guide.
3. Consider a call-blocking app, but note that the FCC doesn't endorse any listed products.
4. Check your voicemail regularly so you don't miss wanted calls that were filtered, as the FCC suggests (FCC).

So should I answer or not?

Use the labels as hints, not verdicts:

• Labeled "spam" or "scam likely": let it go to voicemail. A legitimate caller can leave a message.
• Shows a checkmark but asks for money or personal data: hang up anyway. Call back on a number from your statement or the organization's official website, as the FCC advises.
• Pressure to pay with gift cards, or to act right now: the FCC says that's a scam.

If you get an illegal or spoofed call, you can file a complaint with the FCC, choosing "unwanted calls" and noting whether your number was spoofed, blocked or mislabeled (FCC). You can also look up the number on NoCall.

This article is informational, not legal advice.