System and method for providing a timestamp packetized data interface between an RF unit and a modem. According to one embodiment, the RF unit receives an inbound RF signal, processes and demodulates the inbound RF signal to generate samples, generates a timestamp indicative of when the inbound RF signal was received, packetizes and multiplexes the samples and the timestamp, and sends the multiplexed stream to the modem. The modem generates received data from the samples. If the received data type requires a response to be sent at a particular time, the modem generates symbols from responsive outbound data, generates a timestamp which indicates when the outbound data is to be transmitted, packetizes and multiplexes the symbols and the timestamp, and sends the multiplexed stream to the RF unit. The RF unit generates an outbound RF signal from the symbols, and transmits the outbound signal in accordance with the timestamp.