Answering and saying nothing is a popular tactic, and it is perfectly safe. Just don't expect too much from it. Silence changes how that one call plays out; it doesn't change whether your number gets called again.

What happens on the other end

Automated diallers ring many numbers at once. When a call is answered, software tries to tell a human from a voicemail greeting, often by listening for a short "hello" followed by a pause. If it hears nothing, a few things can happen:

  • the system treats the answer as uncertain and drops the call;
  • it connects you to an agent anyway, who then says "hello?";
  • it plays a recorded message regardless.

Either way, the network recorded that the call was answered. Your number has shown itself to be in use, just as it would if you had spoken.

Does silence protect you?

Not from anything that matters. Saying hello was never the risky part, so staying quiet doesn't add protection for your phone or accounts. Where silence helps is time: some systems give up on quiet lines faster, and you avoid the small risk of being drawn into a conversation with a pushy agent.

What silence doesn't do is remove you from lists. Diallers usually treat an answered call as a live number whether or not you spoke.

Why spam calls are often silent too

If you answer and hear nothing, the silence may be on their side. When a dialler connects more calls than it has agents, some answered calls are left with nobody to take them. Ofcom treats silent and abandoned calls as persistent misuse and limits how call centres use them, but they still happen, especially from operations that ignore the rules. We cover this in what it means when a number calls you then hangs up.

A better approach than silent answering

  1. Let unknown numbers go to voicemail when you can. A real caller leaves a message.
  2. Check the number on Who Rang before calling back.
  3. Block numbers that keep calling and report them to 7726 from your mobile.
  4. If you get silent calls repeatedly from the same number, report them to Ofcom; if they are sales calls, report them to the ICO.

Our take: silence is a fine habit if you like to pick up, but it's not a strategy. The things that actually reduce spam are screening, blocking and reporting, and the spoken version of this question is answered in what happens if you answer a spam call and say hello.