Some signs that your phone could be tapped include unusual sounds during calls, lowered battery capacity and long shut down time. Other indicators of possible tapping and spy software include warm battery temperature, unusual text messages and high data usage.
Clicking sounds, static or distant voices over a phone connection could be indicators of tapping. These are not normal on digital phone networks, states BullGuard. Also, long shut down times can be indicative of spy software, as smartphones must finish all processing tasks before they can turn off. If a data transfer is in transmission, it must also finish before the smart phone can turn off.