V.22bis

What Does V.22bis Mean?

V.22bis is an ITU Telecommunication Standardization Sector (ITU-T) standard that extends the V.22 standard by providing a faster transmission rate using quadrature amplitude modulation (QAM) at 600 baud to carry digital data at 1,200 or 2,400 bits per second, although the 1,200 bit rate is more compatible with the standard.

V.22bis is pronounced "v-dot-twenty-two-biss."

Techopedia Explains V.22bis

V.22bis was developed in 1984 to allow synchronous and asynchronous 2,400 bps full duplex modems to be used on dial-up lines and two-wire leased lines.

Modems that adhere to V.22 standards are intended for use on general switched telephone network (GSTN) connections and on point-to-point, two-wire leased telephone circuits.

The important features of V.22 modems are:

• Channel separation using frequency division
• Inclusion of test facilities, scrambler, compromise and adaptive equalizers
• Duplex mode of operations on point-to-point leased circuits and GSTN
• Data signaling rates of 2,400 bps synchronous, 2,400 bps start stop, 1,200 bps synchronous and 1,200 bps start stop
• Compatibility with a V.22 modem operating in 1,200 bps signaling rates and automatic bit rate recognition
• Quadrature amplitude modulation for every channel with synchronous line transmission at 600 baud