A method and system of processing sampled voice packets from a voice packet sender for transmission over a bit-rate sampled data transmission system, such as by a cable modem over a cable modem termination system, to a voice packet recipient. Unsolicited grant arrivals in response to a request from the voice packet sender coupled to the cable modem are determined. The storing of sampled voice packets is synchronized with the unsolicited grant arrivals. Upon receipt of an unsolicited grant arrival, currently stored sampled voice packets are transmitted to the cable modem for further transmission to the voice packet recipient over the cable modem termination system.