How to Silence Unknown Callers?

On iPhone, go to Settings → Apps → Phone → Silence Unknown Callers and turn it on. On older iOS versions the path is Settings → Phone → Silence Unknown Callers. Calls from numbers not in your contacts then go straight to voicemail without ringing.

On iPhone, step by step:

1. Open Settings.
2. Tap Apps → Phone (on iOS 17 and earlier, just Phone).
3. Scroll to Silence Unknown Callers.
4. Toggle it on.

The calls still appear in your Recents list and can still leave voicemail — they simply don't ring.

What iPhone still lets through: Apple is smarter than a plain contacts check. Calls ring normally if the number is in your Contacts, in your recent outgoing calls, or suggested by Siri from your Mail and Messages. So if you emailed a plumber last week, their call should still ring.

On Android the wording and location vary by manufacturer, because the Phone app differs between Google, Samsung, and others.

Google Phone app (Pixel and most stock Android):

1. Open the Phone app.
2. Tap the three dots → Settings.
3. Tap Blocked numbers.
4. Turn on Unknown (blocks calls from unidentified callers), or
5. Go to Settings → Caller ID & spam and enable Filter spam calls.

Samsung Galaxy:

1. Open the Phone app.
2. Tap the three dots → Settings.
3. Tap Block numbers.
4. Toggle Block unknown/private numbers.

Some Samsung versions also offer Smart Call or Caller ID and spam protection, which flags suspected spam rather than silencing everything unknown.

The trade-off worth knowing before you switch it on. This setting is blunt: it silences every number not already known to your phone. That includes:

• Delivery drivers trying to find your address
• Doctors, clinics, and pharmacies calling back
• Job interviewers and recruiters
• Schools or childcare
• Banks calling about genuine fraud alerts
• Anyone calling you from a new number or a hospital switchboard

Because of this, get into the habit of checking Recents and voicemail once a day while it's on. Many people turn it on during a spam wave and switch it off afterwards.

Gentler alternatives:

• Focus modes (iPhone) — allow calls only from contacts during set hours, so unknown numbers ring during the working day but not at night.
• Carrier spam filtering — most US carriers offer free spam-blocking (T-Mobile Scam Shield, Verizon Call Filter, AT&T ActiveArmor) that blocks known spam rather than all unknown callers.
• Third-party apps like Truecaller or Hiya screen against a database of reported numbers.
• Google Call Screen on Pixel answers unknown calls with an assistant and shows you a live transcript, letting you pick up if it's genuine. This is the best of both worlds if you have it.

Blocking one specific number instead: on iPhone, open Recents, tap the ⓘ beside the number, scroll down and tap Block this Caller. On Android, long-press the number in your call log and choose Block.

Does it stop spam texts? No — this is a call setting only. For texts, use Settings → Apps → Messages → Filter Unknown Senders on iPhone, or the spam protection built into Google Messages.