It’s quite unlikely that someone has tapped your phone while you’re not aware of it. If you are trying to determine if your phone is tapped, there are a few things to consider.
-Is the ringer on? Because tapping into a line that makes noise is pretty noisy and might be noticed by potential recipients. So first make sure it is off or near the speaker volume max setting (again this would need to be done outside).
-Are you using wi-fi instead of data or 4g services? Wi fi signals can hop from one signal source to another in order for connections on devices with multiple radios, so any connection could potentially be an attack vector – if you’re using our phone solely as a wi-fi “hotspot” then you’re probably safe.
If your phone is currently in use as an actual phone (and wasn’t recently used for data services) then it’s most likely not tapped.
-Does the ringer suddenly go off when you make or receive a call? This could be due to lack of charge in the battery, or it could be due to someone who knows what they’re doing tapping into your line. The latter is pretty unlikely unless you are an incredibly high profile target. If someone at your location starts typing on a computer keyboard while you make/receive a call, this represents another potential attack vector because many phones use keystroke audio – meaning it sounds like someone typing as you talk.
-Do loud noises happen near the phone? This is another potential attack vector that we’ve seen used outside of hacking into a mobile phone line. It usually involves using a very loud sound (a short burst from a speaker for example) and aiming it at the target’s cell phone.
The idea is that the phone’s microphone will pick up the sound and transmit it to the target’s ears. The benefit of this approach is that you can be miles away from your victim when he/she hears the gunshot-like sound (the downside is that it usually requires being in close proximity to your target). If you hear loud noises via your phone’s ear piece, it might be best to disconnect the call (if possible).
-Is the screen dimmed? This is another potential indicator of someone nudging into your line because some phones have a dimming feature that automatically turns off the screen after X minutes of inactivity. If you wake up your phone and notice that the screen is dimmed or turned off, then you might be under attack.
-Is the volume of the phone muted? Is it on silent mode? This also could indicate that someone is poking around your phone’s settings to turn down your ring volume before trying to tap into your line. The benefit of turning off the volume would also allow attackers to turn off your speaker or headset temporarily without you realizing it.
-Is the phone plugged into a power source? If you keep your phone on, and all of a sudden the battery goes dead as if someone pulled out the plug – this might be another indication that something is going on with your line, especially during calls (because phones typically don’t get that much power from USB or wall adapters).
-Is the phone warm to the touch? Similar to above, if you’re using your phone normally and it suddenly starts getting warmer – there might be something going on. Keep in mind however that smartphones / cellphones do generate quite a bit of heat when doing intensive tasks such as running rich graphics, playing music and/or videos, etc – so it’s easy to mistake that heat generation with someone trying to attack your phone.
-Is the battery draining quickly? On the flip side of above, if you’re using your phone at full blast (and pretending like nothing is going on) then it might not be a bad idea to check your battery consumption.
