释义 |
V.21 V.21 (protocol, standard)An ITU-T modem protocol for 300bps two-wire full-duplex communications using Frequency Shift Keying modulation.
All modern modems support both V.21 and the close variant,Bell 103.V.21An ITU standard (1964) for asynchronous 0-300 bps full-duplex analog modems for use on dial-up lines. It uses FSK modulation. |