A system comprising: one or more processors; one or more accelerometers; one or more proximity sensors; and one or more non-transitory computer-readable media including one or more sequences of instructions which, when executed by the one or more processors, causes: establishing, by a mobile device, a voice call via a wireless network, wherein establishing the voice call causes one or more wireless transmitters of the mobile device to transmit wireless signals at a transmit power level; obtaining proximity data from the one or more proximity sensors, the proximity data corresponding to a proximity of the mobile device to a detected object; obtaining an acceleration signal from the one or more accelerometers, the acceleration signal corresponding to an acceleration of the mobile device over a period of time; calculating a first power of the acceleration signal within a first frequency band; calculating a second power of the acceleration signal within a second frequency band, wherein the second frequency band is higher than the first frequency band; determining the motion state of the mobile device based on the first power and the second power; and adjusting the transmit power level based on the determined motion state of the mobile device and the proximity data. one or more processors; one or more accelerometers; one or more proximity sensors; and one or more non-transitory computer-readable media including one or more sequences of instructions which, when executed by the one or more processors, causes: establishing, by a mobile device, a voice call via a wireless network, wherein establishing the voice call causes one or more wireless transmitters of the mobile device to transmit wireless signals at a transmit power level; obtaining proximity data from the one or more proximity sensors, the proximity data corresponding to a proximity of the mobile device to a detected object; obtaining an acceleration signal from the one or more accelerometers, the acceleration signal corresponding to an acceleration of the mobile device over a period of time; calculating a first power of the acceleration signal within a first frequency band; calculating a second power of the acceleration signal within a second frequency band, wherein the second frequency band is higher than the first frequency band; determining the motion state of the mobile device based on the first power and the second power; and adjusting the transmit power level based on the determined motion state of the mobile device and the proximity data. establishing, by a mobile device, a voice call via a wireless network, wherein establishing the voice call causes one or more wireless transmitters of the mobile device to transmit wireless signals at a transmit power level; obtaining proximity data from the one or more proximity sensors, the proximity data corresponding to a proximity of the mobile device to a detected object; obtaining an acceleration signal from the one or more accelerometers, the acceleration signal corresponding to an acceleration of the mobile device over a period of time; calculating a first power of the acceleration signal within a first frequency band; calculating a second power of the acceleration signal within a second frequency band, wherein the second frequency band is higher than the first frequency band; determining the motion state of the mobile device based on the first power and the second power; and adjusting the transmit power level based on the determined motion state of the mobile device and the proximity data.