No Caller ID calls: what they are and how to handle them

A No Caller ID call is a normal phone call where the caller's number has been withheld before it reaches you. The caller did one of two things:

• Blocked it for that one call by dialing *67 before your number (see what *67 does).
• Set their whole line to private, so every call they make hides their number automatically (carrier per-line blocking).

Different phones label the same thing differently: iPhone tends to show No Caller ID, Android often shows Private or Unknown, and landlines may show Blocked or Anonymous. They all mean the same thing — the number was intentionally withheld. Note this is different from Unknown/Scam Likely, where the number is visible but your carrier has flagged it.

There are a few common sources:

• Spam and scam callers hide their number so you can't block or report it easily, and so you're more likely to answer out of curiosity.
• Legitimate private callers — some doctors' offices, recruiters, debt collectors, and people calling from a personal line deliberately withhold their number.
• Someone who blocked their own caller ID for privacy and isn't doing anything malicious.

Because the number is hidden, you can't tell which of these it is before answering — which is exactly why blocking or silencing them wholesale is often the practical move.

iPhone can't block a specific hidden number (there's no number to block), but it can silence all of them at once:

1. Open Settings → Phone.
2. Turn on Silence Unknown Callers.

Now any call from a number that isn't in your contacts, recent outgoing calls, or Siri suggestions — including every No Caller ID call — is silenced and sent straight to voicemail. You'll still see it in your recents if you want to check. The trade-off: genuine first-time callers who aren't saved in your contacts get silenced too, so it's best on a personal line, not a business one.

The steps vary by manufacturer, but most Android phones offer one of these in the Phone app:

• Block unknown / hidden numbers: Phone app → ⋮ menu → Settings → Blocked numbers → turn on Unknown or Block calls from unidentified callers.
• Silence unknown callers: on Pixel and some others, Phone app → Settings → Spam and Call Screen or Caller ID & spam lets you filter or screen unknown callers.

Samsung phones label it Block unknown/private numbers under the Phone app's settings. Once on, hidden-number calls are rejected or sent to voicemail automatically.

Mostly, no — that's the point of the feature — but there are a few options:

• *69 (call return) — dials back the last number that called you on many carriers. It usually will not work for a number that was deliberately withheld, but it's worth a try.
• *57 (malicious caller trace) — on many US carriers this logs the details of the last call with the carrier for law-enforcement follow-up. You don't see the number yourself — it's recorded on the carrier's side and typically used after harassing calls. Fees may apply.
• *77 (Anonymous Call Rejection) — a landline/VoIP feature that automatically rejects calls with a withheld caller ID; the caller hears a message to unblock their number and call again. Dial *87 to turn it off. Availability varies by carrier.

Beyond these, there's no reliable consumer way to unmask a hidden number — apps that promise to are generally not trustworthy.