An ITU fax standard (1991) that uses TCM modulation at 12,000 and 14,400 bps for Group 3. It adds TCM to the V.29 standard at 7,200 and 9,600 bps to allow transmission over noisier lines. It also defines special functions (echo protection, turn-off sequences, etc.) for half-duplex operation. Modulation use is a half-duplex version of V.32bis.