Why do spam or scam calls hang up when you answer? | campus.sg

scam calls
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Have you ever been bothered by random unknown numbers calling your mobile phone and then hanging up as soon as you answer? It’s not just you – it’s a pretty common occurrence these days, and it’s happening worldwide.

There are two likely scenarios when you get a phone call and then it hangs up as soon as you answer.

Scenario 1: It’s a robocall to ascertain your number’s real

These robocalls – which are automated and thus have no human behind it – are simply programmed to make sure that your telephone number is legit, and not some second number you don’t use. Once you answer, or say ‘hello’, it will disconnect because it knows you actually use your number.

Once that happens, your number will be added to a database which the company the robocall belongs to can then sell onto other people.

In the best-case scenario, the number is simply sold to institutions like insurance companies or banks, and then you’ll find yourself getting persistent calls asking you to buy life insurance or invest in a new bank account.

In the worst-case scenario, it is run through networks that trawl through social media accounts to look for traces of your number. The information is then collated to formulate some sort of scam to convince you that you owe money. The usual protocol is for them to ask you for your credit card information, passwords, etc.

Your number can also be used in an act called Caller ID Spoofing. This means that your number is used by the scammers to call other people in Singapore and pretend to be from a local institution, like a bank or government branch, and convince recipients they owe money.

Scenario 2: It’s a call centre bot

The call could come from a Predictive Dialer, which is an outbound calling system from a call centre that automatically dials from a list of telephone numbers. The system makes random calls non-stop because the idea is to quickly connect you to an agent who is just finishing a call – that way, they get maximum work out of the agents.

It uses “voice energy” to detect answering the phone – when the system hears you answer the phone, it’ll switch the call to an available agent. If no agent is available immediately, you think you have a dead line so you hang up.

But, if you answer the phone softly, the system can’t detect the phone’s been answered. And if you pick up and delay saying ‘hello’, the system will think the call’s gone to a voicemail. In both cases, it won’t connect to the agent and will hang up.

What should you do?

Most people will know not to answer strange numbers they don’t recognise. However, if you’re in no position to not answer random calls, you can download the ‘Should I Answer’ app which blocks calls you flag, and also blocks other numbers other uses have flagged.

Singapore just launched ScamShield for iOS users, which is a mobile app that filters scam calls and messages from known scam numbers. You can also register with the Do Not Call (DNC) Registry to opt out of marketing messages here.