What actually works
Spam call blockers, honestly compared
The short answer
There are four kinds of spam call blocker and they are not interchangeable. Your phone’s built-in filter and your carrier’s filter are free and catch numbers already flagged by other people. Blocker apps add a bigger shared list. Call screening is the only one that handles a number nobody has reported yet — which is most of them, because the numbers rotate constantly.
Checked on iOS 26.0–27.x, Android 15–16 · Updated October 18, 2026
- Free options
- Phone + carrier
- Catches known numbers
- All four
- Catches new numbers
- Screening only
- Setup
- 1–10 minutes
Your phone’s built-in filter (free, 1 minute)
iOS 26 and later
Calls your carrier has already flagged as spam skip the ring and go to voicemail.
Open Settings > Apps > Phone and turn on Spam.
- Settings
- Apps
- Phone
- Spam
From the makers of this guide
Want the calls screened, not just silenced?
PhoneShield answers your calls first. Known scam numbers are refused before your phone rings, the people you know ring straight through, and everyone else is asked who they are and why they’re calling, so your doctor and the delivery driver still reach you.
Your carrier’s filter (free, a few minutes)
Verizon Call Filter, AT&T ActiveArmor and T-Mobile Scam Shield all block or label known spam on the network, before it reaches your handset. Turn this on even if you use something else — it is free and it works upstream.
Install or open your carrier’s app and enable spam blocking. Paid tiers add caller ID lookups.
- Carrier app
- Spam blocking
Third-party blocker apps (free to about $4 a month)
Several apps match incoming calls against a large shared database built from user reports, and sell a paid tier with extra caller ID lookups.
Install the app and grant it call-identification permission in your phone’s settings.
- Settings
- Apps
- Phone
- Call Blocking & Identification
Call screening — the only one that handles unknown numbers
Screening does not ask "is this number on a list?" It asks the caller who they are and why they are calling, then decides. That is why it works on numbers that have never been seen before.
On iOS 26 and later: Settings > Apps > Phone > Screen Unknown Callers > Ask Reason for Calling.
- Settings
- Apps
- Phone
- Screen Unknown Callers
For something that also refuses reported scammers outright and lets family straight through, a screening service runs the same idea on your number.
Beyond this setting
What else helps
The one gap every free option shares
Built-in filters, carrier filters and blocker apps all work from lists of numbers other people already reported. Spam operations know this, which is why they burn through thousands of fresh numbers — by design, you are the one who reports it after being called. Screening is the only approach that does not need to have seen the number before. PhoneShield refuses numbers already reported as scams *and* asks everyone else what they want, so unknown-but-legitimate callers still reach you. No app, no permissions, works on any phone including a parent’s.
How call screening works →Check a number before you call back
Reports on millions of U.S. numbers, updated daily, free.
Check a number →Stack the free ones anyway
Carrier filter plus the built-in Spam toggle costs nothing and removes a real share of the volume. Do both regardless of what else you use.
Carrier steps →Got a specific number?
Check who’s been reporting it
See how often people reported a number to the FTC, what the calls were about, and what to do, at isthisnumberascam.com.
Questions
What people ask
What is the best spam call blocker?
For known spam numbers, your carrier’s free filter is as good as most paid apps and runs before the call reaches you. For numbers nobody has reported yet — the majority — only call screening helps, because it asks the caller rather than checking a list.
Are paid call blocker apps worth it?
They add a larger shared database and better caller ID than the free tiers. They do not solve the core problem: a brand-new number is on no list anywhere, and new numbers are most of what reaches you.
Why do spam calls get through my blocker?
Because blockers match against lists of previously reported numbers. Spam operations rotate through thousands of fresh numbers and fake local ones specifically so there is nothing to match.
Does blocking a number stop it calling?
It stops that one number reaching you. It does not remove you from the dialling list, so the operation simply calls from the next number it owns.
Do I need an app to stop spam calls?
No. The built-in Spam filter and your carrier’s filter are free and cover known numbers. An app adds a bigger list; screening adds the ability to handle numbers that are not on any list.
Sources
Checked against
Every step is checked against the official instructions. Menus change with updates; tell us if one has moved.