13-2 C HAPTER 13: H ANDSHAKING, ERROR CONTROL, DATA COMPRESSION, AND THROUGHPUTSelective Reject is an optional part of the ITU-TV.42 (LAPM) standardAttaining Speeds Above 28.8 KbpsV.34 connections at 21.6, 24, and 26.4 Kbps are common. To getconnections of 28.8, 31.2, and 33.6 Kbps, line quality must be pristineend-to-end. In addition, 31.2 and 33.6 Kbps connection rates arepossible only when the device to which you are connecting also runssoftware that supports speeds above 28.8 Kbps.Attaining 56 K ConnectionsWhen a clientV.90 modem connects to a server V.90 modem, the paththrough the telephone network between the modems is subject to thefollowing conditions for anV.90 connection to be made.A digital connection at one en d ISPs or other online services musthave a digital connection to the public switched telephone network(PSTN). Most major online services have a digital connection to the PSTN.Only one digital-to-analogue convers i o nThere can be only onedigital-to-analogue conversion in the telephone network between theV.90 server modem and the V.90 client modem.Controlling the V.8 Call IndicateToneThe V.8 protocol speeds call negotiation and specifies a call indicate tone.Providing the call indicate tone is optional. For compatibility, we ship theCourier V.Everything modem with the call indicate tone disabled.For your modem to CommandEnable Selective Reject ATS51.6=0 (Default)Disable Selective Reject ATS51.6=1For your modem to CommandEnable the call indicate tone ATS54.6=0
