Current smartphone inputs are limited to physical buttons, touchscreens, cameras or built-in sensors. These approaches either require a dedicated surface or line-of-sight for interaction. SideSwipe is a novel system that enables in-air gestures both above and around a mobile device. Our system leverages the actual GSM signal to detect hand gestures around the device. We developed an algorithm to convert the discrete and bursty GSM pulses to a continuous wave that can be used for gesture recognition. Specifically, when a user waves their hand near the phone, the hand movement disturbs the signal propagation between the phone’s transmitter and added receiving antennas. Our system captures this variation and uses it for gesture recognition.