How to Tell If Your Phone Is Being Spied On: 9 Signs and What to Do
Updated: 3 days ago
A battery that dies mid-afternoon, a phone that is warm lying on the table, someone who always seems to know where you have been and who you have talked to. People who come to us asking “how do I know if my phone is being spied on” rarely suspect an unknown hacker: they suspect someone close to them. In this guide we explain the signs to look out for, what you can check yourself on iPhone and Android, what you should not do and when it makes sense to request a professional electronic sweep.
Quick answer: how do I know if my phone is being spied on?
No single sign proves your phone is being spied on. What you should take seriously is a combination of several: battery and mobile data draining faster for no apparent reason, heat while idle, apps or profiles you did not install, unknown sessions on your accounts and, above all, someone who knows things that were only on your phone. You can rule out the simplest cases with the checks below. To be sure, a technical analysis of the device is needed.
The 9 signs your phone may be being spied on
1. The battery drains much faster
A spying app works in the background: it records, stores and sends information. That uses power. If your phone now needs charging mid-day and you have not changed how you use it, it is worth investigating. Keep in mind that a battery that is a few years old also loses capacity.
2. The phone heats up when you are not using it
Heating up during a game or a video call is normal. Heating up while lying on the table with the screen off suggests something is working without you seeing it.
3. Mobile data use has increased
The information collected has to be sent somewhere, and that uses data. In your phone settings you can see usage by app: look for names you do not recognise or figures that do not make sense.
4. Apps you did not install appear
Spying apps rarely show their real name. They disguise themselves as “system service”, “sync” or “update”. Go through the full list of installed apps, not just the icons on the home screen.
5. The phone has become slow or behaves strangely
A screen that lights up on its own, takes a long time to switch off, unexpected restarts, apps that close for no reason. These are weak signs when they appear alone, because an old phone or one with little storage does the same, but they count when combined with others.
6. You receive messages or codes you did not ask for
Verification codes you did not request, sign-in alerts from a new device or messages with strange strings of characters may mean someone is trying to get into your accounts, or already has.
7. There are unknown sessions or devices on your accounts
Often nothing is installed on the phone: the person has logged in to your Apple or Google account, or linked your WhatsApp to another device, and follows everything from there. On WhatsApp, check Settings, Linked devices. We explain this case in detail in the guide on cheating on WhatsApp and the legal mistakes to avoid.
8. Settings changed without you touching them
Location always on, microphone or camera permissions granted to apps that do not need them, installation of apps from unknown sources allowed, protection switched off. Someone had to change those settings.
9. Someone knows things they should not know
It is the most important sign and the only one with no innocent technical explanation. If a person repeats private conversations, turns up where you are or knows plans you only shared by message, the information is leaking somewhere. It could be the phone, but it could also be a GPS tracker in the car or a listening device at home.
What you can check yourself
These checks do not replace a technical analysis, but they let you identify the most common situations. Menu names vary by brand and system version. To see whether your calls are being forwarded, use the code *#21#. And if your concern is phone tapping, read how to tell if your phone is being tapped.
On iPhone
Installed profiles. In Settings, General, VPN & Device Management, there should be no profile you do not recognise. If you do not use a company phone, this area is normally empty.
Devices on your Apple account. In Settings, tap your name and go through the list of devices. Remove any that are not yours.
Safety Check. In Settings, Privacy & Security, Safety Check shows who you are sharing your location and data with, and lets you cut off that access.
App list. Scroll through the App Library to the end and confirm that you recognise every app.
On Android
All apps. In Settings, Apps, choose to see all apps, including system apps, and look for generic names you do not recognise.
Accessibility. It is the permission most used by spying apps, because it lets them read what appears on screen. No app you do not know should have this access.
Device administration. In the security settings, see which apps have administrator privileges.
Play Protect. In the Play Store, confirm that protection is on and that nobody has switched it off.
Devices on your Google account. In your Google account management, under Security, see the devices that are signed in.
What not to do
Do not confront the person you suspect. If they have access to the phone, they can delete everything before you can confirm.
Do not factory-reset straight away. It solves the problem in most cases, but it destroys the evidence. If you are considering filing a complaint, you will need it.
Do not search or ask for help from that phone. If you are in fact being monitored, the other person finds out that you suspect. Use another device.
Do not install “anti-spy” apps at random. Many detect nothing and some are a risk themselves.
A safety note. If the person you suspect has been violent or controlling, removing their access may alert them and make the situation worse. Before touching the phone, speak to the authorities or to APAV, the Portuguese victim support association, through its free Victim Support Line, 116 006.
Who usually installs spying apps
In our experience, it is almost never a stranger. It is the spouse or ex-partner, a relative, a business partner or someone at the company. In most cases the installation takes a few minutes with the unlocked phone in hand, which is why someone who knows the passcode or has access to the device is in a better position to do it. In companies, information leaks can have other origins, and in those cases it makes sense to also check meeting rooms and offices.
Is it a crime to spy on someone else's phone in Portugal?
Being married, living together or being a business partner does not give you the right to access another adult's phone. Installing a spying app without consent, logging in to another person's accounts or reading their communications may constitute the crime of illegitimate access (Cybercrime Law), violation of correspondence or telecommunications and invasion of privacy (Penal Code). If you confirm that you were a victim, you can file a complaint with the PSP, the GNR, the Judicial Police or the Public Prosecutor's Office. This text is informational: a lawyer can assess your specific case.
When to request a professional phone sweep
The checks above catch the simplest situations. It makes sense to request a professional analysis when the signs accumulate, when someone keeps knowing too much after you have changed your passwords, when you need to be sure before making a decision or when you want to document what was found.
How our phone sweep works
It is in person. The device is handed over to our team. We do not provide this service remotely.
iPhone and Android. We analyse both systems.
12 hours. We need the device with us for 12 hours.
Report at the end. When we return the phone, we hand over a report of what was found.
Booking in advance. The service is scheduled in advance, so that we can guarantee the availability of the technical team.
The service is part of our technological investigations and is coordinated by detective Alexandre Ribeiro. We only analyse the devices of our clients: we do not access third parties' phones or accounts.
What to do now: 4 steps
1. Record the signs
Note down dates and specific situations: when the battery ran out, what the other person knew that they should not have known, what strange messages you received.
2. Do the basic checks
Go through the lists of apps, profiles, permissions and devices linked to your accounts. Take photos of the screen with another device before changing anything.
3. Protect your accounts from another device
Change the passwords for your email, your Apple or Google account and your social media, and turn on two-step verification. Do it on a computer or a phone you trust.
4. Ask for professional confirmation
If doubt remains, an electronic sweep can confirm or rule out the suspicion and leave you with a report of what was found.
Frequently asked questions about spied-on phones
How do I know if my phone is being spied on?
Look for a set of signs rather than a single one: battery and data draining faster, heat while idle, apps or profiles you did not install, unknown sessions on your accounts and, above all, someone who knows things that were only on the phone. The checks in this guide help rule out the simplest cases; confirmation requires a technical analysis of the device.
Can a phone be spied on without anyone touching it?
It can happen, for example through access to your Apple or Google account or a WhatsApp session open on another device. Even so, in most of the cases that reach us, the spying app was installed by someone who had the phone in hand and knew the passcode.
Does a factory reset remove the spying app?
In most cases, yes. But it also removes the traces that it ever existed. If you are considering filing a complaint, ask first for an analysis that documents what is installed. And remember that, if the source is access to your accounts, resetting the phone does not solve the problem.
Is it a crime to install a spying app on someone else's phone?
It can be. Installing a spying app on another adult's phone without their consent, or accessing their accounts and communications, may constitute a crime in Portugal, even between spouses. A lawyer can assess your specific case.
Do you analyse both iPhone and Android?
Yes, we analyse both systems. The service is in person: the device stays with us for 12 hours and, at the end of that period, is returned with a report of what was found.
How long does a phone sweep take?
We need the device with us for 12 hours. Booking is made in advance, so that we can guarantee the availability of the technical team.
Think your phone is being spied on?
Talking to us is confidential and carries no commitment. We carry out in-person sweeps across the country, including Lisbon, Porto and the Algarve. Call +351 936 225 975 or use our contact page.
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