Turn on Silence Unknown Callers by going to Settings, then Phone, then Silence Unknown Callers, and switching it on. On newer iPhones, you may need to open Settings, tap Apps, then Phone. Apple says the feature is available on iOS 13 and later, and it sends unknown callers to voicemail while still showing them in Recents [source: Apple].
TLDR: Silence Unknown Callers is the fastest built-in way to stop random numbers from making your iPhone ring. If 10 spam calls hit your phone in a week, this can turn all 10 into silent voicemail entries instead of loud interruptions. For example, if a car warranty scam calls during a meeting, your phone stays quiet, but the call still appears in Recents. Just remember that real callers not saved in your contacts may also be silenced.
What Silence Unknown Callers actually does
Silence Unknown Callers does not block every unknown number. It simply stops your iPhone from ringing when the number is not recognized. The caller is sent to voicemail. The call also appears in your Recents list, so you can check it later.
Your iPhone will still ring for certain people and numbers, including:
- People in your Contacts
- Numbers you recently called
- Numbers Siri finds in Mail, Messages, or other suggestions
This setup is handy because it cuts down on junk calls without fully shutting the door. If someone leaves a useful voicemail, you can call back. If it is spam, you can ignore it with zero guilt.
How to turn it on
The setting is easy to miss. Honestly, it feels like Apple tucked it one screen deeper than it needed to be. Still, once you know where it lives, it takes about 15 seconds.
- Open the Settings app.
- Scroll down and tap Phone.
- If you use iOS 18 or later, tap Apps, then tap Phone.
- Tap Silence Unknown Callers.
- Switch on Silence Unknown Callers.
That is it. There is no extra setup. No spam list to build. No app to install. Your iPhone starts filtering unknown callers right away.
When you should use it
This feature is great if your phone keeps buzzing with robocalls, fake delivery updates, loan offers, or numbers from random area codes. It is also useful if you work from your phone and hate being pulled away from real tasks.
Use it if:
- You get several spam calls a week.
- You rarely answer numbers you do not know.
- You prefer voicemail over surprise interruptions.
- You want a free option built into the iPhone.
It drives me crazy that one junk call can break your focus for no reason. This setting helps stop that without making you install yet another call filter app.
When you should not use it
There are times when Silence Unknown Callers can be annoying. If you are waiting for an important call from an unknown number, turn it off for a while.
Be careful if you are expecting calls from:
- A doctor’s office
- A school
- A delivery driver
- A repair technician
- A hiring manager
- A bank fraud team
Here is a simple use case. Say you applied for five jobs this week. A recruiter may call from a number you have never seen. If the setting is on, the call may go straight to voicemail. That is not a disaster, but it could cost you time if you miss the message.
How to avoid missing real calls
The best trick is simple: save key numbers before they call. Add your doctor, school, workplace, landlord, bank, and family members to Contacts. Then your iPhone knows those callers are allowed through.
You can also do this:
- Turn the feature off temporarily when waiting for a call.
- Check voicemail daily if unknown calls matter to you.
- Review Recents to spot missed calls from real people.
- Ask companies to text first when possible.
If someone calls once and you call them back, future calls from that number may be allowed through because your iPhone sees it as a recent outgoing call. That small detail helps a lot.
What about blocked numbers?
Silencing and blocking are not the same thing. Silencing sends unknown callers to voicemail. Blocking stops a specific number from reaching you again in the normal way.
To block a number:
- Open the Phone app.
- Tap Recents.
- Tap the info button next to the number.
- Scroll down and tap Block Caller.
Use blocking for repeat pests. Use Silence Unknown Callers for the wider mess of random numbers.
Extra tips for fewer spam calls
Silence Unknown Callers is a strong start, but it is not the only tool. Many carriers also offer spam labeling or call filtering. Check your carrier’s app or account page. Some features are free. Others cost extra, which is annoying when the calls were not your fault in the first place.
You can also report junk texts and calls when your carrier supports it. For texts, many carriers let you forward spam to 7726, which spells “SPAM” on a phone keypad.
For most iPhone users, though, the built-in setting is enough. Turn it on, save the numbers you care about, and let unknown callers explain themselves in voicemail.