Block Spam Calls at the Carrier: US Cellular, T-Mobile, AT&T, Verizon

US Cellular — Call Guardian (free)

1. Install the US Cellular Call Guardian app, or sign in to My Account on uscellular.com.
2. Open Call Guardian and turn on Block on the High-risk category so flagged fraud calls never ring.
3. Set Medium-risk to Label, so a warning appears on screen but real calls still get through.
4. Use Report a number inside the app for anything that slips past — it feeds the shared network list.

T-Mobile / Metro — Scam Shield (free)

1. Dial #662# from your T-Mobile line and press call. A confirmation text arrives in seconds.
2. Check it is active with #787#. Turn it off again with #632#.
3. For per-category control, install the Scam Shield app and set Block for scam and Label for likely nuisance.

AT&T — ActiveArmor (free)

1. Install AT&T ActiveArmor Mobile Security and sign in with your wireless number.
2. Open Calls → Block suspected spam and turn it on.
3. Add nuisance categories (telemarketing, surveys, political) under Personal block list.

Verizon — Call Filter (free tier)

1. Open the Call Filter app that ships on Verizon phones, or install it from your app store.
2. Turn on Spam filter and set the level to High to auto-block the worst offenders.
3. Turn on Spam alerts so any remaining suspect call is labelled on screen.

How do I block spam calls on US Cellular?

US Cellular includes Call Guardian free. Install the Call Guardian app or open My Account, then set High-risk calls to Block and Medium-risk to Label. Blocked calls never ring your phone, and you can report any number that gets through from inside the app.

Is US Cellular Call Guardian free?

The blocking and labelling tier is free on every US Cellular line. A paid premium tier adds reverse number lookup and personal block lists, but you do not need it to stop scam calls.

What is the code to block scam calls on T-Mobile?

Dial #662# and press call to switch Scam Block on. #787# checks whether it is on, and #632# turns it off. It works from the dialler with no app installed.

Which carrier blocks spam calls best?

All four major US networks now block known fraud numbers at no charge, and in practice the difference is small. The bigger gain comes from stacking: carrier block plus your phone's own filter (iPhone Silence Unknown Callers, Android spam filtering) catches far more than either alone.

Does blocking at the carrier stop the calls reaching my phone?

Yes. Carrier blocking happens on the network before the call is routed to you, so your phone never rings and no voicemail is left. Phone-level filters only act after the call arrives.

Do I still need to register with the Do Not Call list?

It is worth doing at donotcall.gov, but it only binds legitimate telemarketers. Criminal robocallers ignore it entirely, which is why carrier blocking matters far more.