3Com 56K manual Glossary

12GLOSSARY

V.17 An ITU-T standard for facsimile operations that specifies modulation at 14.4 Kbps, with fallback to 12 Kbps.

V.21-FaxAn ITU-T standard for facsimile operations at 300 bps. 3Com or compatible fax devices then transmit or receive at higher speeds.

V.21-ModemAn ITU-T standard for modem communications at 300 bps. Modems made in the U.S. or Canada follow the Bell 103 standard. However, the modem can be set to answer V.21 calls from overseas.

V.22 A ITU-T standard for modem communications at 1200 bps, compatible with the Bell 212A standard observed in the U.S. and Canada.

V.22 bis An ITU-T standard for modem communications at 2400 bps. The standard includes an automatic link negotiation fallback to 1200 bps and compatibility with Bell 212A/V.22 modems.

V.23 An ITU-T standard for modem communications at 1200 bps with a 75 bps back channel. Used in the U.K.

V.25 An ITU-T standard for modem communications. Among other things, V.25 specifies an answer tone different from the Bell answer tone. All 3Com modems can be set with the B0 command so that they use the V.25 2100 Hz tone when answering overseas calls. (Not applicable to the Business Modem.)

V.25 bis An ITU-T standard for synchronous communications between the mainframe or host and the modem using the HDLC or character-oriented protocol. Modulation depends on the serial port rate and setting of the transmitting clock source, &X. (Not applicable to the Business Modem.)

V.27ter An ITU-T standard for facsimile operations that specifies modulation at 4800 bps, with fallback to 2400 bps.

V.29 An ITU-T standard for facsimile operations that specifies modulation at 9600 bps, with fallback to 7200 bps.

V.32 An ITU-T standard for modem communications at 9600 bps and 4800 bps. V.32 modems fall back to 4800 bps when line quality is impaired, and fall forward again to 9600 bps when line quality improves.

V.32 bis An ITU-T standard that extends the V.32 connection range: 4800, 7200, 9600, 12K and 14.4 Kbps. V.32 bis modems fall back to the next lower