Abstract: A method and apparatus of transmitting a modulated data over a digital voice network that includes voice compression. The method and apparatus determine whether a voice signal to be transmitted over the network includes a modulated data signal and then encodes or demodulates the modulated data signal and bypasses voice compression when a modulated data signal is detected. The method and apparatus may detect a modulated data signal by detecting the presence of an answer tone and then searching for a plurality of phase reversals having a particular time distance from each other in the voice signal. Once the encoded or demodulated signal is transmitted over the digital voice network, the method and apparatus of the present invention may detect whether the received signal is an encoded data signal or a demodulated data signal. Then the coded data signal may be decoded back into a modulated data signal. Likewise, the demodulated data signal may be modulated back into a modulated data signal.

Abstract: A method and apparatus of detecting a tandem link and performing tandem tunneling when a tandem link is detected. The detection of a tandem link includes generating a HAIL and ACK signal where a voice compression unit on one end of the link receives the signals and generates an ACK signal for a voice compression unit on the other end of the link when the HAIL signal is detected. The tandem tunneling prevents the VCUs that comprise the tandem link from decompressing packets received on a network link, adds HDLC header information to the packet to generate HDLC framed packets on the subscriber side, removes HDLC header information from HDLC framed packets received on the subscriber side, and passes the unframed packets to the network side.