Low riskPhone & Voice

Number Harvesting Robocall Scam

In this scam, robocalls with silence, a simple question, or a generic recording aim to confirm your number is active and reachable, marking it for more scam calls or recording responses for misuse.

Quick verdict

Risk level
Low risk
Scam type
Number validation (robocall)
Main red flag
A robocall with silence or a yes-or-no question like 'Can you hear me?'
What to do first
Do not respond; hang up rather than saying 'yes' or pressing keys.

What to know first

In this scam, robocalls with silence, a simple question, or a generic recording aim to confirm your number is active and reachable, marking it for more scam calls or recording responses for misuse.

Phone and voice scams, known as vishing, use live callers and robocalls to impersonate banks, retailers, agencies, and tech support. The call is a doorway to remote access, one-time codes, or moving money, and phone contact carries some of the highest reported losses.

The core pattern to watch for is clear: A robocall with silence or a yes-or-no question like 'Can you hear me?' Do not respond; hang up rather than saying 'yes' or pressing keys.

Related tricks worth knowing: the One Ring Call Scam and the Caller ID Spoofing Scam. For the wider picture, browse the Phone & Voice Scams guides or run the message through our scam checker.

Scam statistics

Highest median loss
phone calls are the contact method with the highest reported median loss to fraud
Source: US Federal Trade Commission
$2.7B
reported lost to imposter scams in the US in 2023
Source: US Federal Trade Commission

Tell-tale red flags

  • Silence or dead air when you answer
  • A simple yes-or-no question to prompt a response
  • A generic recording with no real purpose
  • Calls that hang up once you answer
  • An uptick in scam calls afterwards

Staying safe

  • Hang up rather than responding or pressing keys
  • Do not say 'yes' or confirm details to robocalls
  • Use call-blocking and your carrier's spam tools
  • Report persistent robocalls

How it usually reads

Example pattern, not a real report
Example pattern: A call opens with silence or asks 'Can you hear me?' to get a 'yes' and confirm your number is live.

This is a fictional, anonymised example used to illustrate the pattern. It is not a verified real message, and any names are used only to show how the scam typically reads.

What to notice: A robocall with silence or a yes-or-no question like 'Can you hear me?'

Steps if you already acted

  • If you engaged, simply be alert for more scam calls
  • Do not act on any follow-up that cites your 'response'
  • Block numbers and tighten call filtering
  • Report it to your carrier

Common mistakes

  • Do not say 'yes' or answer prompts
  • Do not press keys to be removed
  • Do not engage with silent or generic robocalls

Scams like this one

Low risk Text Message

One Ring Call Scam

In this scam, also called Wangiri, a single ring comes from an international or premium-rate number hoping curiosity makes you call back, connecting you to a costly premium line that charges by the minute.

Created by Scam or Safe Editorial Team
High risk Phone & Voice

Caller ID Spoofing Scam

In this scam, fraudsters fake the caller ID so a call appears to come from your bank, a local number, or a real agency, making their impersonation far more convincing.

Created by Scam or Safe Editorial Team
Medium risk Phone & Voice

Survey & Research Call Scam

In this scam, a caller claims to be conducting a survey or market research, then asks probing questions to harvest personal and financial details, or offers a 'prize' that needs a fee or card details.

Created by Scam or Safe Editorial Team

Your questions answered

Why do robocalls stay silent or ask 'can you hear me?'
They confirm your number is active and reachable, marking it for more scam calls, and may record your voice. Hang up rather than responding.
Is saying 'yes' dangerous?
The bigger risk is confirming your number is live, leading to more calls. Avoid responding, and never authorise anything based on a recorded 'yes'.
How do I cut down these calls?
Use call-blocking and your carrier's spam tools, do not engage, and register with any call-preference service available.
Should I press a key to opt out?
No. Pressing keys confirms your number is active and usually leads to more calls. Just hang up.

Last reviewed June 2026 · Written & reviewed by the

Disclaimer: This page provides educational information only to help you recognise common scam patterns. It is not legal, financial, cybersecurity, or law enforcement advice, and it does not confirm whether any specific message, company, or person is genuine or fraudulent. When in doubt, contact the official organisation directly and report concerns to your local authorities.