Calls from mystery numbers can be a nuisance, especially if you’re trying to avoid scams or avoid talking to someone you don’t recognize right away. But there are two different ways that those undefined numbers can be marked in your iPhone: No Caller ID and Unknown Caller. So, what’s the difference?

Here’s what to know about each label, and how you can protect yourself from potential call scams.

No Caller ID vs. Unknown Caller

A call marked “No Caller ID” means that the caller has blocked their number from showing up on your screen. In other words, they want to hide their identity. This can be a privacy measure, but it’s also a tool used by scammers — if you can’t quickly Verify who is calling based on their number, you can easily fall into their trap.

“Unknown Caller,” on the other hand, is the message that appears when your telephone service provider does not recognize who is calling. This can be caused by many reasons, including network or technical issues, or receiving calls from Foreign number. Usually, these callers don’t intend to hide their identity, but it’s still good to be careful scammers can also use this method to mask their identity by using an unregistered phone in the company of phone for example.

What to do if you receive unknown calls

You should always proceed with caution if you do not recognize a caller. This is especially important if someone calls you and “No Caller ID” appears on the screen, because they are hiding their number on purpose. But an Unknown Caller is also something to watch out for, because it can be very difficult to know who is on the other end of the line.

Allowing the call to go to voicemail is usually a good idea. Simply answering a call is a signal to scammers that your number is active, which can lead to many similar calls in the future. the Live Voicemail feature is especially helpful for these situations because it allows you to pick up the call if the voicemail transcript shows that it is someone you want to talk to.

Silence unknown callers on your iPhone

You can even go a step further and silence unknown callers on your iPhone. That way, those mysterious callers won’t disturb you, and they can just leave a voicemail for you to check later.

On your iPhone, go to Settingsthen tap Applications followed by phone and go to Silence Unknown Callers. Press the toggle to turn it on.

Check it out: Why Are You Getting So Many Spam Calls?

08:33

Use apps to block unknown calls

Although there is no way to block these unknown calls within your iPhone settings, your the wireless carrier may offer apps to help it.

AT&T ActiveArmorfor example, there is a free version that blocks spam and fraud calls, and also allows you to block all unknown callers. The advanced version, which costs $4 a month, includes tools like reverse number lookup and caller ID for unknown numbers. ActiveArmor is available for iOS and Android.

Verizon’s Call Filter app also offers spam detection, spam filtering and the option to report numbers, all for free. For an additional $4 a month, you also get caller ID, spam lookup, a personal block list and a spam risk meter. Call Filter is automatically enabled for Android users on a postpaid plan, and is available in the App Store for the iPhone.

T-Mobile Scam Shield there is a free option that includes full caller ID, scam reporting and scam blocking. There’s also a premium option for $4 a month per line, which offers reverse phone number lookups and voicemail transcriptions automatically texted to you. You can download the Scam Shield app at App Store or Google Play.

Be sure to check with other wireless carriers to see if they offer the same. Some wireless carrier plans may include access to premium features as well.

For more third-party apps to help limit robocalls and general tips, check out our guide to stop spam calls.