V.120 is an ITU standard for transfer of asynchronous serial communication (like those usesd with traditional analog modems in the PSTN) via ISDN B-channels. This standard was mostly used in North America, while in Europe, X.75 was more frequently used.
comparison to other protocols¶
It is, like V110, a true V-series adaptation protocol capable of producing/replicating modem status lines.
Hoewever, unlike V110, V.120 is a HDLC based protocol.