<
standard> The
ITU-T standard defining interchange circuits between
DTE and
DCE. V.24 is the
ITU-T equivalent of
EIA standard
EIA-232C, though V.24 only specifies the meaning of the signals, not the connector or the voltages used.
V.24 recommends 12
modem carrier frequencies that will not interfere with Dual Tone Multi-Frequency or other telephone control tones. These are:
GROUP A = 920 Hz, 1000 Hz, 1080 Hz, 1160 Hz GROUP B = 1320 Hz, 1400 Hz, 1480 Hz, 1560 Hz Group C = 1720 Hz, 1800 Hz, 1880 Hz, 1960 Hz