ITU-T V.42

This Recommendation describes error-correcting protocols for use with V-series duplex DCEs to accept start-stop data from the DTE and transmit in synchronous mode. This Recommendation contains and HDLC-based protocol referred to as the Link Access Procedure for Modems (LAPM). This revised version of the Recommendation adds the capability for suspension and resumption of error correction in support of the V.92 modem-on-hold feature. The negotiation parameters for V.44 data compression are added for reference. This revision also gives guidance on the use of answerer detection patterns in a new Appendix VI. Annex A and Appendix V of the previous versions are now deleted in the 2002 revision. The remaining annex and appendixes have not been renumbered.