A method of wireless communication. The method includes the step of transmitting at least a first sub-frame from a first voice frame. If the first sub-frame is received by the wireless unit, an acknowledgement message is transmitted, and the remaining sub-frames from that voice frame are not transmitted. If the first sub-frame is not received by the wireless unit, however, a non-acknowledgement message is transmitted. Here, the base station retransmits at least another sub-frame from the first voice frame.