Note the high battery temperature. When you talk, the battery is discharged. Normally when during this process, the battery heats up. But if you do not touch the phone, and he's still hot, so something is working, for example, spyware.
Mobile device quickly loses its charge. A new phone some time ago on one charge worked for a few days, suddenly began to very quickly lose their charge - so it works for some app. It is possible that it is spyware.
Off delay. Pay attention to the turn-off time and backlight. In the case where the shutdown continues for a long time or fails immediately to execute this process, the backlight is flashing or on, then the phone is something strange. Of course, this can be a common technical problem or malware. In any case, you need to take the phone to a technical service.
The strange behavior of the equipment. The phone turns off, reboots, turns on the backlight, install and run the program, in short, leads an independent life, then most likely he's under the wire. Do not disregard these phenomena, although it is possible variant of the common technical problems of the operating system.
Interference and crosstalk. If during conversations you hear echo, noise or any type of interference, then it is an occasion to reflect. On the one hand, they can be the consequence of bad reception, but if the interference is permanent, you should worry. Interference are those sounds that we hear his mobile phone, for example, the speaker. They can be when talking on the phone or from time to time, when the phone asks for the base station. In the case where extraneous sounds from the speakers is audible even when the phone is at rest, then the device is tapped.