Is Someone Listening to Your Phone Calls and How to Stop It
By Simon Lewis
Updated:
Phone call privacy is something most of us take for granted, but there are real ways that someone could listen in on your conversations without your knowledge.
The good news is that for most people, the risk is manageable, and there are straightforward steps you can take to protect yourself.
In this article, we’ll walk through how phone eavesdropping actually works, the signs to watch out for, and what you can do to stay protected.
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How Could Someone Listen to My Phone Calls?
People can use a few different tools to listen to your phone calls. Some tools are installed especially for the purpose of hacking your device, whereas others make use of vulnerabilities in existing apps in order to bypass security.
Spy apps
Spy apps, or spyware, are commercially available tools that can be purchased for as little as $30. These apps are often very easy to install, requiring very little technical knowledge. They can:
- Allow access to many features of the device onto which they are installed. This includes not only phone calls, but also text messages, emails, internet browsing activity, and more.
- Hack both Android and iOS devices. iOS requires the device to be jailbroken or the use of malicious configuration profiles. Android devices are more susceptible, but the hacker may have to change a few simple security settings.
Many spy apps are available on the market, but the two most commonly used apps are FlexiSpy and mSpy. Both of these apps have more or less the same function, as described above.
How common is phone spyware?
Spyware is more prevalent than many people assume. According to Certo’s 2024 Mobile Security Roundup — based on analysis of nearly 700,000 device scans — 6.26% of scanned devices showed medium or high security threats, with commercial spyware tools including mSpy and FlexiSpy among the most commonly detected. See the full report.
Zero-day exploits
Zero-day exploits occur when a hacker discovers a vulnerability in an app or device that the manufacturer is unaware of. This means that the hacker can fully exploit the vulnerability to attack the user’s device.
Although the information a hacker can obtain differs depending on the circumstances, it’s quite common for Zero-day exploits to give access to phone calls.
A recent example is DarkSword, an iPhone exploit originally used by surveillance vendors that has since leaked online. A device running an older version of iOS can be compromised simply by visiting a malicious website in Safari.
Once inside, attackers can access messages, passwords, and the device microphone, potentially including live calls. Read Certo’s full coverage here.
Because these hacks are initiated before device manufacturers have a chance to react, they are usually left scrambling to find a solution as quickly as possible to reduce the window of vulnerability for their customers.
That’s why keeping your phone and apps updated is so important.
SS7 network vulnerabilities
A less well-known but real threat comes not from your device, but from the telecommunications network itself. SS7 (Signaling System 7) is the decades-old protocol that phone networks still use globally to route calls and texts.
Its outdated design means that sophisticated attackers — typically state-sponsored actors or well-resourced surveillance vendors — can exploit its weaknesses to intercept calls at the network level, without ever touching your phone.
Unlike spyware, there’s no app you can uninstall to fix an SS7 attack — the vulnerability exists in the network infrastructure.
The good news: this type of attack requires significant resources and technical capability, making it far less common than spyware for the average person.
If you’re concerned, switching to encrypted calling apps like Signal (which routes calls over the internet, bypassing SS7 entirely) is the most effective defense available to consumers.
Expert Insight
“In my experience working in mobile security, the phone call eavesdropping threat people most need to worry about isn’t a sophisticated government wiretap — it’s commercial spyware installed by someone with brief physical access to their device. We see this in the scan data regularly. The good news is that this type of spyware is detectable, and removing it is entirely within reach for the average person.”
— Simon Lewis, Co-founder, Certo Software
Some Misconceptions about Phone Call Eavesdropping
Not every form of phone surveillance gives someone access to your calls, and it’s worth knowing the difference.
Family tracking apps, for example, are widely used for monitoring GPS location but have no capability to intercept audio. Attacks that target iCloud or Google accounts can expose synced photos, messages, and passwords, but live phone calls are not stored in the cloud and can’t be accessed this way.
In practice, it’s usually only the most intrusive spyware and network-level exploits that can actually capture call audio. Most other threats are focused on data collection — harvesting passwords, tracking movements, or accessing messages — rather than listening in on conversations.
It’s also worth clearing up a common myth: knowing someone’s phone number alone is not enough to eavesdrop on their calls. Despite what circulates online, a phone number gives an attacker no direct route to your microphone or call audio.
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🎥 How to Tell if Someone is Listening to Your Phone Calls
How to Tell if Someone Is Listening to Your Calls
Spyware is designed to stay hidden, so spotting it isn’t always straightforward.
That said, there are several warning signs worth looking out for — and a few practical checks you can run right now to find out if something suspicious is going on.
High data usage
Spyware constantly sends data from your phone back to whoever is monitoring you. That background activity adds up — and often shows up as an unexplained spike in your mobile data usage.
To check on iPhone, go to Settings > Cellular (or Mobile Service on some devices) and scroll down to see which apps are using the most data.
Fig 1. Checking for apps with high data usage on iOS.
On Android, go to Settings > Network & Internet > Data Usage to view a breakdown by app.
Fig 2. Checking for apps with high data usage on Android.
If an app you don’t recognize or rarely use is near the top of the list, that’s worth investigating.
Battery issues
Spyware runs continuously in the background, recording activity and transmitting it to a remote server. That takes processing power, which drains your battery faster than normal.
To check on iPhone, go to Settings > Battery to see which apps have been using the most power over the last 24 hours or 10 days.
Fig 3. Checking for apps with high battery usage on iOS.
On Android, go to Settings > Battery > Battery Activity (By tapping the graph). An unfamiliar app showing high battery consumption is a red flag.
Fig 4. Checking for apps with high battery usage on Android.
Slow performance
If your phone feels sluggish — apps taking longer to load, the UI stuttering, or the device running warm for no obvious reason — it could be a sign that something is running in the background without your knowledge.
Occasional slowdowns are normal. But if it’s persistent and out of character for your device, it’s worth considering spyware as a possible cause alongside other explanations like a failing battery or the device running low on storage space.
Background noise
Strange sounds during a call — clicking, static, or faint echoing — are sometimes flagged as a sign of eavesdropping. It’s worth knowing, but treat this one with caution: poor signal and network issues are far more common causes of audio interference than spyware.
That said, there have been documented cases where spyware has caused unusual audio artifacts during calls, so it’s not something to dismiss entirely. If you’re hearing strange noises regularly and can’t explain them through signal or network issues, it’s worth investigating further.
App permissions
Malware needs access to your microphone to record your calls. Reviewing which apps currently have that permission is one of the most direct ways to spot something that shouldn’t be there.
iPhone: Go to Settings > Privacy & Security > Microphone. You’ll see a list of every app that has requested microphone access, along with whether that access is currently on or off.
If you see an app you don’t recognize — or one that has no obvious reason to need your microphone — revoke its access immediately.
Fig 5. Checking microphone permissions on iOS.
iOS also has an App Privacy Report that logs exactly when any app accessed your microphone, camera, or other sensors. To enable it, go to Settings > Privacy & Security > App Privacy Report and turn it on. Check back after a day or two to see a detailed timeline of microphone activity.
Android: Go to Settings > Security and Privacy > Microphone. This shows every app that has microphone access, split by whether permission is set to “Allow all the time,” “Allow only while using the app,” or “Don’t allow.”
Any app listed under “Allow all the time” that you don’t recognize should be investigated.
Fig 6. Checking microphone permissions on Android
Hidden spyware
Some spyware is specifically designed to hide itself. It may not appear in your app list, may disguise itself with a generic system-sounding name, or may show no icon at all. Manual checks won’t always catch it.
Running a spyware scan with a dedicated tool is the most reliable way to uncover hidden threats.
Certo’s apps for iPhone and Android are built specifically for this — scanning your device for known spyware, suspicious configurations, and other signs of compromise that standard checks miss.
Fig 7. Detecting spyware with Certo for Android.
Private conversations known
One of the most telling signs that your calls are being monitored is when someone knows the contents of a conversation they weren’t part of.
If a partner, ex, or colleague references something you only discussed over a private phone call, that’s a significant red flag.
This can sometimes be explained by coincidence or an overheard conversation — but if it happens repeatedly, or if the details are too specific to be guesswork, take it seriously. In domestic situations particularly, this is often one of the first signs that a device has been compromised.
Need Support?
If you’re concerned that a partner, ex-partner, or someone close to you is monitoring your calls, you’re not alone — and help is available.
Certo is a proud member of the Coalition Against Stalkerware, a global network of organizations working to combat technology-facilitated abuse. If you’re in this situation, you can find support resources at certosoftware.com/resources.
How to Prevent Someone from Listening to Your Calls
The most effective defenses against phone call eavesdropping are also some of the simplest.
These steps won’t just protect your calls — they’ll make your device significantly harder to compromise in the first place.
Strong passwords and screen locks
If someone can’t get into your phone, it’s much less likely they can install spyware on it. A strong screen lock is your first and most important line of defense.
On iPhone, go to Settings > Face ID & Passcode (or Touch ID & Passcode) and ensure you’re using a six-digit PIN or alphanumeric passcode rather than a four-digit code.
Fig 8. Setting up a passcode on iOS.
On Android, go to Settings > Security and privacy > Screen lock and choose PIN, password, or biometric lock. Avoid patterns as they’re easier to guess.
Fig 9. Setting up a screen lock on Android.
Regular software updates
Most malware relies on known vulnerabilities in out-of-date software. Keeping your device updated is one of the most effective ways to close those doors before attackers can use them.
On iPhone, go to Settings > General > Software Update and turn on Automatic Updates.
Fig 10. Checking for updates and turning on Automatic Updates on iOS
On Android, go to Settings > Software Update.
Fig 11. Checking for updates and turning on Automatic Updates on Android.
If your device no longer receives updates from the manufacturer, treat it as a security risk and consider upgrading.
Be cautious with app installations
Only download apps from official sources — the App Store for iPhone, and the Google Play Store for Android.
Apps distributed outside these stores often bypass the security review process entirely, and malicious apps disguised as legitimate ones are a common spyware delivery method.
Even within official stores, apply some scrutiny. Check reviews, look at the developer’s other apps, and pay attention to what permissions an app requests during installation. A weather app asking for microphone access is a warning sign, not a quirk.
Use encrypted communication apps
For sensitive conversations, consider using an end-to-end encrypted calling app. Signal and WhatsApp both offer encrypted voice and video calls that are routed over the internet rather than through traditional phone networks — bypassing SS7 vulnerabilities entirely.
This won’t protect you if spyware is already installed on your device, but it does add a meaningful layer of protection against network-level interception.
For everyday use, Signal in particular is widely regarded as the gold standard for private communication.
Avoid jailbreaking or rooting
Jailbreaking an iPhone or rooting an Android device removes the built-in security restrictions that Apple and Google have put in place.
While it can unlock additional features, it also strips away protections that keep malicious apps from accessing sensitive parts of your device — including your microphone.
Jailbroken and rooted devices are significantly easier to install spyware on, often without the owner realizing. If you’ve previously jailbroken your device, consider restoring it to its factory state to reinstate those protections.
Limit physical access
Most consumer spyware requires someone to physically handle your device for a few minutes to install it. Keeping your phone with you, or locked in a secure place when you’re not using it, removes that opportunity.
Be particularly mindful in situations where someone with a potential motive has unsupervised access to your device — whether that’s a partner, an ex, a colleague, or anyone else. Brief physical access is all it takes.
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How to Tell If Your Landline Phone Is Tapped
A tapped landline is less likely these days, but it’s definitely still possible. If you suspect your landline has been compromised, here are some signs to look out for:
- Background noise: As with mobile devices, background noise while on a call can be a sign that you have an unauthorized listener. Listen out for static, buzzing or clicks on the line.
- Interference around other electronic devices: If you notice interference with other electronic devices, such as your cell phone or even your TV, it could be a strong sign that there is a listening device in the building. These devices often use signals that can affect the normal operation of some electronic devices.
- Strange noises from the phone when not on a call: When you pick up the phone to make a call, before you dial any numbers, listen to the receiver and see if you can hear any unusual noises other than the dial tone on the line.
- Phone box looks tampered with on the outside of the house: If you notice that the landline box on the outside of your home looks like somebody has tampered with it, it could be a sign that something out of the ordinary is going on. It may be that someone has forced the box open in order to fit a listening device. Any engineers who need access to the box will have the appropriate tools to access the box.
- Strange utility trucks or workmen around the property: If you see utility trucks or workmen directly around your property, ask them for credentials. If you’re worried, call the company listed on the truck and ask them to check that the workers are legitimate. Sometimes, phone tappers can disguise themselves as utility workers in order to gain access to a landline box without arousing suspicions from onlookers.
If you’re suspicious of a landline tap, you can get a “landline tap detector” to give you a definite answer.
These are easily purchased from a number of different websites and stores. It might be worth contacting a local home security company who may be able to help you get this set up.
Wrapping Up
The idea of someone listening to your private calls is unsettling, but it’s worth keeping the threat in perspective. For most people, the risk comes not from sophisticated government wiretaps, but from commercially available spyware that requires brief physical access to your device to install.
The good news is that the same basic habits that protect against most cyber threats apply here too: keep your software updated, use a strong screen lock, and stay mindful of who has access to your phone.
If you’re concerned your device may already be compromised, don’t rely on guesswork. Certo AntiSpy is designed to detect spyware that manual checks miss — giving you a clear answer and the tools to act on it.
Frequently Asked Questions
Can someone listen in without touching my phone?
Yes, in rare cases. Sophisticated spyware tools like Pegasus and DarkSword can compromise a device remotely — in some cases simply by visiting a malicious website.
Additionally, SS7 attacks can intercept calls at the network level without any software on your device at all.
These threats require significant technical resources and typically target journalists, activists, or high-profile individuals rather than everyday users.
Can someone listen using just my phone number?
No. A phone number alone isn’t enough to access your calls. It requires either software installed on your device or a sophisticated network-level attack.
Does airplane mode stop eavesdropping?
Not reliably. It cuts off real-time transmission, but some spyware stores recordings locally and uploads them once a connection is restored. Removing the spyware entirely is the only real fix.
What’s the quickest way to check if I’ve been compromised?
Review your microphone permissions and check for unusual data or battery usage. For a thorough check, run a deep scan for spyware with Certo AntiSpy.
By Simon Lewis
Simon is the co-founder of Certo and a hands-on cybersecurity expert with over 15 years of experience. Holding an honours degree in Computer Forensics, he personally built Certo's first apps and previously consulted for companies and law firms on hacking incidents, fraud, and intellectual property theft. He now channels that expertise into making cybersecurity tools and knowledge accessible to everyone.