Telegraph-Telephone Terminal AN/MCC-6 The AN/MCC-6 is an air- or vehicular-transportable assemblage used to provide FDM carrier telegraph and carrier telephone facilities in an area type communications system. The AN/MCC-6 provides two 12-channel telephone systems. It also provides 16 channels of teletypewriter (tt). All 16 channels of tt may be put on one voice channel, 8 tt channels may be put on each of two voice channels, or 4 tt channels may be put on each of four voice channels. When a voice channel is used for tt circuits, it reduces the voice channel capability by one. Only one 12-channel system can be used over spiral-four cable for a distance greater than 5 miles. The AN/MCC-6 is used with a radio repeater, such as the AN/MRC-103 or AN/MRC-54, as a terminal in a radio relay system. (Source: FM 24-25, June 1977)