Independent guides to unwanted calls and texts. We never look up, identify or track people.

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Independent guides to unwanted calls and texts. We never look up, identify or track people.

Explainer

Carrier Spam-Blocking Services: What They Do and Don't Do

Short answer

The three national US carriers each run a free network service that labels or blocks likely spam, plus a paid tier with extra tools. This is where the 'Scam Likely' tag comes from, and where call authentication (STIR/SHAKEN) fits in. It helps a lot, but no carrier can stop every spam call, so it works best layered with your phone's own settings.

Compare the carrier services

We don't run a lookup service and never ask for your number, contacts, or account details.

Defense, not lookup: This guide is about blocking and labeling spam you receive, not identifying private people.
Independent: We are not affiliated with any carrier; check the carrier's own page for current plans.
Honest limits: Labeling reduces spam and never promises to eliminate it, per the FTC.

A cell tower sending calls through a filter: some pass, some are marked as spam risk and stopped. — Illustration, not a real phone interface.

What each carrier service offers

Free network protection plus a paid upgrade; features and prices vary by plan and change over time.

Scroll the table sideways on a small screen.

Option	Free spam or scam labeling	Auto-blocks highest-risk calls	How you turn it on	Paid upgrade with extras
T-Mobile / Metro — Scam Shield	Supported Flags likely scams as 'Scam Likely' on your screen.	Conditions apply Only after you turn on Scam Block, e.g. by dialing #662#.	Supported Labeling runs by default; dial #662# to add the stronger Scam Block option.	Supported A premium tier adds enhanced caller ID; price changes, so check t-mobile.com.
Verizon — Call Filter	Supported Spam detection and alerts on eligible plans and devices.	Supported Sends high-risk spam to voicemail on eligible plans.	Supported Often on automatically for eligible plans and devices; manage it in the Call Filter app or My Verizon.	Supported Call Filter Plus adds caller ID, a spam-risk meter and block-by-category; check verizon.com.
AT&T — ActiveArmor	Supported Suspected-spam labeling on AT&T wireless and prepaid.	Supported Automatic fraud-call blocking on the network.	Supported The free service runs on the network; manage it in the ActiveArmor app.	Supported An advanced tier adds identity and monitoring extras; check att.com.
Your phone's own spam filter (iPhone / Android)	Conditions apply Uses your carrier's spam verdict or the phone's own spam check: flagged calls are silenced and moved to a Spam list.	Conditions apply Silences or filters flagged calls once you turn the filter on.	Supported Set up in your phone's call settings; see our iPhone and Android guides.	Not available The built-in phone filters are free.
MVNO / prepaid brands	Conditions apply Some resellers ride the host network's labeling; many offer a subset or none.	Conditions apply Only if the host network passes its blocking through; many prepaid brands offer none.	Not available Often no carrier setting to enable; rely on your phone's built-in labeling.	Not available A paid spam tier is frequently unavailable on prepaid brands.

Note: Carrier features, tier names and prices vary by plan and region and change over time; always confirm on the carrier's own page. Labeling and blocking reduce spam but do not eliminate it.

checked September 2026

What carrier blocking really promises

Each of these is true and useful, and each has a limit worth knowing up front.

It labels many likely spam and scam calls before you answer.

The limit: Shady calls still come through with a warning; a label is not a block.
On some carriers, or once you turn it on, the free tier auto-blocks or diverts the highest-risk calls.

The limit: Spoofers rotate numbers, so some new spam always slips past.
It works best layered with your phone's own block and silence settings.

The limit: No single tool stops every spam call; combine carrier, phone and reporting.
Call authentication (STIR/SHAKEN) lets carriers check that the caller ID was not altered in transit on IP networks.

The limit: It does not cover every network, and a verified mark means the number checked out, not that the caller is honest.

Note: No carrier, app or guide can promise to block all spam forever, and we never claim to identify who is calling.

Carrier spam terms, in plain words

Tap a term to see what it means before you rely on it.

Scam Likely: A T-Mobile network label for calls it thinks are scams. It is a carrier tag, not a universal standard, and it warns rather than blocks unless you turn on auto-block.
STIR/SHAKEN: A caller-ID authentication framework the FCC required carriers to adopt. The originating carrier signs the number and the receiving carrier checks the signature, which erodes spoofing on IP networks.
Other carriers' spam labels: Each carrier words its warning differently, such as Potential Spam or Suspected Spam, and names change by carrier, app and plan; treat any label as a warning, not proof.
Scam Block (auto-block): An opt-in carrier setting that stops calls already flagged as likely scams from ringing; T-Mobile customers can turn it on by dialing #662#. It only catches calls the network has flagged.
Call labeling: The carrier or phone tagging a call as spam or scam based on known-bad databases and analytics. It reduces how often you answer spam; it does not remove the calls.

See all terms

Questions people ask

Does my carrier's spam blocking cost anything?

The three national US carriers each offer a free network service that labels and, for the riskiest calls, blocks or diverts spam. They also sell a paid tier with extras like enhanced caller ID and a spam-risk meter. Prices and tier names change, so confirm on t-mobile.com, verizon.com or att.com. Prepaid and reseller brands may offer only a subset.

What is a 'Scam Likely' call?

'Scam Likely' is T-Mobile's label for calls its network flags as probable scams. It is a warning on your screen, not an automatic block, so the call can still ring unless you turn on Scam Block by dialing #662# or using the Scam Shield app. Other carriers use their own labels.

If a call shows 'Verified', is it safe to answer?

Not necessarily. A verified or checkmark tag comes from STIR/SHAKEN authentication, which checks that the caller ID number was not altered in transit on IP networks; it does not cover every network and says nothing about whether the caller is honest. Treat urgency, secrecy or requests for gift cards, wires or codes as scam signs no matter what the label says. How spoofing still gets through: What Is Caller ID Spoofing? A Plain Explanation.

Will carrier blocking stop every spam call?

No. Labeling and blocking reduce spam, but scammers rotate spoofed numbers and new ones get through, and the FTC is clear that these tools cut down calls rather than end them. Layer your carrier service with your phone's own settings and report the worst calls.

Can my carrier tell me who is behind a spam number?

No, and neither can we. Carrier services and this guide are about labeling, blocking and reporting calls you received, not unmasking a private person from a number. If a call is threatening, keep records and contact local police; for illegal calls, report to the FTC at reportfraud.ftc.gov or the FCC.