I've recently had an encounter with the law, the details of which I won't disclose here since the case is still in court. They took my phone, naturally. I deactivated it as soon as I was released later that day and had another phone activated on the same number, since it's the only way most people can reach me. In addition to that line I have a separate work phone. Both are on the same carrier (Sprint), and I usually have rather poor cell phone signal at home. What makes me wonder is that my work phone (older HTC android model) gets signal more consistently, while my primary line (Galaxy S4) frequently shows a red X instead of any signal bars. Quite frequently since the incident occurred I have been unable to use my primary line for up to an hour or more while the work phone has good service. This is sometimes alleviated by restarting it. Is this any indication that a Stingray/IMSI device is intercepting my calls?

  • github.com/SecUpwN/Android-IMSI-Catcher-Detector Looks good, but I've never used it.
    – user49350
    Jun 14, 2014 at 20:42
  • Also, the app doesn't appear complete, so I'm not sure how helpful that would be. Jun 15, 2014 at 12:18
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    They'd have to be bored to be sitting outside your apartment with something to pick up your calls. Remember, the mobile phone is connecting through a network, just like a wired phone. The government doesn't bother going to the endpoint, they just have the central network give it to them. They might be having the network ping the number for data locations more often (or possibly driving by some of the time) to verify your (phone's) location, but I'd start with the device just being faulty. Unless somebody may have hired a PI too? Jun 15, 2014 at 12:24
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    @Clockwork-Muse, I think you need to read the press on the recent abuses of Stingray devices. Jun 16, 2014 at 7:10
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    @JulianKnight - sure, these devices are all over the place. What I'm getting at, though, is that this person has already been arrested, and some of his property confiscated; the police probably have enough to get a warrant for data from the cell companies. If they don't have one, anything such a device collects could (maybe, talk to lawyer) be thrown out - at minimum, the ACLU would love such a case. So the use of the device is really secondary here... Jun 16, 2014 at 9:08

3 Answers 3


The most plausible explanation for a phone with poor reception is that the phone's hardware is faulty in some way (either that specific phone has an issue, or the phone design is flawed). Expensive phones don't necessarily guarantee good reception.

IMSI-Catchers are active devices that pose as fake base stations. Details are not really public; however, it seems that when such a device is active, it cannot (easily, or at all) intercept connections for only one specific phone. Thus, all phones in the vicinity ought to be equally affected. This is not consistent with the symptoms you observe. Therefore, either IMSI-Catchers have become more advanced and selective, or you really are not under that kind of surveillance, and your S4 phone is just bad at radio communications.

  • In order for a IMSI-Catcher to work, they must lure the targeted phone to connect with them instead of the carrier's station. The only way I know without messing with the baseband involves being the "tower" with best reception for the targeted phone. So if a phone gets spied on, its the work phone. However, its still inconsistent.
    – user10008
    Aug 24, 2014 at 16:03

There are a couple of things you should be aware of:

  • Some smartphones will happily re-install all the apps you had on your previous phone, assuming you log on with the same account (say, Google). This means that if somebody managed to install malware on your phone before you had the chance to de-activate it, you might have the same malware.
  • As others pointed out, the network connectivity problem might just be broken hardware. But if you suspect a stingray (e.g. a fake mobile station), you could figure out which codes work on your mobile to display the distance to the nearest tower (based on signal attenuation). A bit of triangulation should do the trick.

Of course, if it's an authorised wiretap, there isn't much you could do, as it's likely being implemented at the mobile operator level.

  • An authorized wiretap is supposed to be invisible to the person being tapped. Stinger is used to mass sweep up phone calls, but for intercepting one person's calls it's way easier and cheaper to serve your carrier with a warrant. Nov 16, 2017 at 16:51

I know existing apps on Android market who can show you the serial number of the official antenna next your home (imsi spy or phone spy detector for example).

Normally, you have like one or two or more antenna next your home, these apps register all serial number and name/number ID, of these antenna. Also you can see at what time and what day you have one new antenna registry on your android phone.

Not bad also to buy one Android phone cheap with new sim card for this test and keep in your home. If someone want to know more of you, he will be interested to place an IMSI catcher to know your details device (and phone number) you use.

I have understand that, if start the IMSI catcher next your home when you are there and after when you are not here, It's possible to see the devices in the listing and out the listing of the IMSI catcher to know what is your device.

Maybe the best isn't to use/turn on, a GSM in your house or in your cars (IMSI catchers are really small!).

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