The MP-2100M-VC-4/FXO four channel PCM module for the Megaplex 2100 / 2104 /4100 that has an FXO interface.brbr The VC-4, VC-8 and VC-16 modules provide 4, 8 or 16 toll-quality analog voice channels. Voice signals are digitized using PCM, in compliance with ITU-T G.711 and AT&T Pub. 43801 standards, for transmitting up to 30 voice channels over an E1 link, or 24 voice channels over a T1 link. In addition to 64 Kbps PCM encoding, VC-4A and VC-8A modules employ toll-quality 24 or 32 Kbps ADPCM voice encoding.brbr The maximum number of voice channels in one Megaplex-2100/2104 unit depends on the chassis, main link modules, number of VC modules, and encoding used. For example, a MP-2100 unit equipped with 8 VC-16 modules, in conjunction with 4 channels of ML-8E1 or ML-8T1, can provide up to 120 voice channels. brbr Features include E&M, FXS or FXO interface options, caller ID, A-law or u-law compounding, optional in band signaling with A-law encoded channels, PCM (64 Kbps) and ADPCM (24 or 32 Kbps) encoding.