Various embodiments facilitate data communication between a client device and a remote device over a voice channel of a telephone system. In one embodiment, the data communication over the voice channel is synchronized to align with voice frames utilized by the telephone system to transmit communicated data between the devices. In some embodiments, the synchronization is performed by determining an offset between a received synchronization audio signal and the voice frames used by the telephone system to process the synchronization audio signal, such as based on an amount of energy present in the received synchronization audio signal.