Someone calls you back saying you called them… but you never called that person?
Strangers are calling you back claiming you tried to reach them? Your number has probably been hijacked by fraudsters: it's called phone spoofing. What it really is, why your SIM card has (most likely) not been hacked, and the right reflexes to adopt.
You pick up your phone and someone says:
“Hello, did you try to call me?”
The problem: you never called them.
A few hours later, another person calls you back with exactly the same question.
Your first reaction will probably be to check your call history, or to wonder whether your phone or SIM card has been hacked.
Rest assured: in the vast majority of cases, your phone has not been hacked and nobody has used your SIM card.
You are most likely a victim of phone spoofing.
What is spoofing?
Spoofing consists of falsifying the number displayed during a phone call.
When a call reaches your phone, the network receives, among other things, a piece of information indicating which number should be displayed.
In certain situations, fraudsters can manipulate that information and present a number that does not belong to them.
They can therefore call someone while making your phone number appear on the recipient’s screen.
The person being called sees your number and naturally assumes the call came from you.
If they don’t answer and later call back the number displayed, it’s your phone that rings.
And yet you never made that call.
Why do fraudsters use real Swiss numbers?
Quite simply because a Swiss number looks far more reassuring than an unknown number from abroad.
Imagine two incoming calls:
- +41 79 xxx xx xx
- a completely unknown international number
Which one are you more likely to answer?
Fraudsters know this perfectly well.
So they sometimes use genuine Swiss numbers belonging to individuals or companies, without their owners’ permission.
Your number may thus be used completely at random.
Does this mean my SIM card has been hacked?
No, not necessarily — and generally not.
In a typical spoofing case, the fraudster does not have your SIM card, has no access to your phone, and does not necessarily even know your identity.
They simply use your number as the displayed caller ID.
It’s comparable to someone sending a letter with your address written as the sender on the envelope.
That doesn’t mean they broke into your home or have your keys.
Do the calls show up on my bill?
Normally, no.
Since the call was not actually made from your subscription, it should not appear in your usage history with your provider.
This is, in fact, one of the ways to tell simple spoofing apart from actual misuse of your line.
If in doubt, you can check your call records in your customer portal or contact your provider.
Why is spoofing so hard to block completely?
The global telephone network is made up of a very large number of interconnected operators.
An international call can therefore travel through several networks before reaching the recipient’s operator.
Historically, part of the telephone system relies on a degree of trust between operators regarding the information transmitted with a call.
Modern networks now have far more advanced control mechanisms, and operators are continually strengthening their detection and filtering systems.
But when a call comes from abroad and displays a falsified Swiss number, determining automatically and instantly whether that call is legitimate can remain complex.
What should you do if your number is being used?
If a few people call you back occasionally, there is generally no need to change your number.
The phenomenon can disappear as quickly as it appeared, as fraudsters regularly rotate the numbers they use.
However, if you suddenly receive dozens of callbacks, contact your provider to report the situation.
And above all:
never share a password, SMS code, PIN code or banking information with someone simply because the displayed number looks legitimate.
The displayed number is therefore not proof of identity
This is probably the most important thing to remember.
A call displaying the number of a bank, a Swiss company or even a public authority does not, on its own, guarantee that this organisation is really behind the call.
If someone asks you for sensitive information and you have the slightest doubt:
hang up.
Look up the official number of the company or organisation concerned yourself and call it back directly.
Don’t just automatically call back the number in your call history.
In summary
If someone calls you back claiming you called them when you didn’t, don’t panic.
Your number has probably simply been used as a caller ID by a third party.
Your phone is not necessarily hacked, your SIM card has most likely not been copied, and your subscription has not necessarily been compromised.
This phenomenon has a name: phone spoofing.
At MaxiConnect, we continuously monitor the security and quality of the communications passing through our services and work with our network partners to limit fraudulent calls as much as possible.
And when it comes to phone fraud, one rule remains essential:
Never trust a call simply because you recognise the number displayed.
