 way achieve better use of the Frame Relay resource? The goal of VoFR is not to replace existing voice networks but rather to make use of what is already available in Frame Relay to carry overflow traffic or additional voice traffic. Voice is compressed in Frame Relay and then encapsulated into the Frame Relay protocol via a FRAD. Again, the main advantage of this is better use of a single data network and the cost savings derived from this efficiency. But remember that if you run everything over a single network, voice quality may suffer, and, even worse, data performance may suffer. The Frame Relay Forum has specified the FRF.11 standard for how to deploy VoFR. It provides bandwidth-efficient networking of digital voice and Group 3 fax communications over Frame Relay. It defines multiplexed virtual connections, up Chapter 7 Wide Area Networking to 255 subchannels on a single Frame Relay DLCI, and it defines support of data subchannels on a multiplexed Frame Relay DLCI. The ITU has defined some VoFR compression standards: ITU G.711 PCM-Regular PCM is the compression standard that was part and parcel of the PDH hierarchy, which carried voice at 64Kbps. That's a very high rate, given what we can achieve today. ITU G.726/G.727 ADPCM-Adaptive Differential PCM (ADPCM) com- pression reduces the data rate to 32Kbps, allowing for more efficient use of bandwidth. ITU G.723.1 MP-MLQ-With Frame Relay networks, we can apply Multi- pulse Maximum Likelihood Quantization (MP-MLQ), which reduces voice to 4.8Kbps and can permit up to 10 voice channels on a single 64Kbps connection. Another important feature of VoFR is voice activity detection (VAD). VAD algo- rithms reduce the amount of information needed to recreate the voice at the desti- nation end by removing silent periods and redundant information found in human speech; this also helps with compression. Another quality issue related to VoFR is jitter, the variation in delays on the receive side of the transmission from one packet to the next. Delay varies, depend- ing on t