Standard transmit levels for domestic (US/Canada) modems are   
      approximately -10 dB, although V.34 negotiates these levels during the   
      initial connection attempt.  Receiving levels can vary widely, depending   
      on the conditions on your local phone line, the line at the remote   
      modem, and any long-distance or inter-office carrier facilities.   
      
      Typical receiving levels range from -40 dB at the low end, to -15   
      dB at the high end, with figures in the -20dB to -35dB range being   
      most common.  Extreme values in either direction probably indicate   
      a problem in the connection from your modem to your local phone   
      company, which in some cases the phone company may be able to   
      adjust.   
      
      However, be aware that Ma Bell and the long distance carriers are   
      not required by law, statute, or tariff to "fix" this "problem" on   
      unconditioned voice grade lines, because it is not really a   
      "problem"!   
      
      Why does it get bad?   
      
      Simple line impairment.   
      
      Variations in line quality are typically the culprit for low   
      connect rates.  Line impairments can result in link timeouts (when   
      the error control protocol does not receive a block of data within   
      its expected time frame), link naks (when the error control   
      protocol requests retransmission of data), blers (block errors;   
      errors in received error control protocol or data blocks), and   
      resent data blocks. Everyone occasionally gets "a bad line" and   
      has to hang up and call again to get a better connection.   
      However, if you find that you never or rarely connect at rates   
      above 19.2kbps, you will want to investigate the line quality of   
      your connections.   
      
          *Try calling a different location.  Line quality differs from   
           region to region, and it may be a problem with the lines or   
           modem at the other end of a particular call.   
      
          *Try connecting with a local call.  Sometimes the connections   
           within a long distance call can cause impairments.  (If this   
           isolates the problem, you can try switching long distance   
           companies.)   
      
          *Try plugging the modem to a different phone line or wall jack.   
      
          *Try eliminating all telephone extensions, phone line surge   
           suppressors, line switches, utility monitoring devices   
           connect to the phone line, and anything else on the line with   
           the modem.   
      
          *If you know someone else in your area with a high speed   
           modem, ask what type of connections they make.  Try making   
           the connection from their location.  If you encounter the   
           same low connection rates, the problem may be resulting from   
           impairments along the lines running to the local telephone   
           company or within your home or office.  Your telephone   
           company or a private consultant may be able to help.   
      
   Question: Why is it that the phone company and some of my friends say that   
   it is impossible for me to operate my 14400 baud modem on a normal phone   
   line? Do I really need on of those costly special lines?   
      
      Answer: This question arises from the improper usage of the term   
      baud in reference to the DCE rate of a modem. It is quite correct   
      that a 9600 -baud- modem will not operate within the bandwidth of a   
      common phone line. It is quite another matter when referring to a   
      14400 -bps- modem (that operates at 2400 symbols/sec), which   
      certainly will.   
      
   Question: I just bought a GENERIC XPRESS V.32bis 14400bps modem but can't   
   connect at 14400 with a system that is running a USR HST 14400 modem,   
   shouldn't I be able to connect at 14400?   
      
      Answer: No, you will only be able to connect at 300, 1200 or   
      2400bps because Bell 103, Bell 212A, and V.22bis are the only   
      mutually supported protocols the modems have. HST is a proprietary   
      protocol which is only available on some of US Robotics' modems.   
      You should be able to connect at 14400bps with any other modem   
      which is ITU-T V.32bis compliant however.   
      
   Question: I just bought a Generic Xpress-Lite 2400 modem with V.42bis, and   
   the package it came in says it can achieve 9600bps throughput. but when I   
   call a system I know operates at 9600bps, I only connect at 2400bps, what's   
   going on, shouldn't I connect at 9600? I also notice that my transfer   
   speeds are only slightly higher than they were with my Generic Lite 2400   
   that didn't have the V.42 stuff (about 285cps using Ymodem-g versus the 238   
   got with Zmodem-MobyTurbo with the Generic Lite 2400), shouldn't I get the   
   1100cps or so that other folks do with 9600bps modems?   
      
      Answer: No, you will only connect at 2400bps because your modem is   
      a 2400bps DCE device. You will get 9600bps DTE data transfer rate   
      between you computer and modem by locking your serial port at   
      9600bps, but -only- achieve modem to modem effective throughput of   
      9600bps if the data you are transferring is in non-compressed form.   
      Note that your base link rate remains 2400bps, but that the data   
      compression of V.42bis is capable of effectively quadrupling data   
      throughput. Regarding transfer speeds, you are doing the best you   
      can do with a modem which operates at a 2400bps DCE. The folks with   
      9600bps modems typically operate with 19200 or 38400bps DTEs and   
      have real 9600bps DCEs.   
      
   Question: While I was glancing through the manual that came with my Generic   
   Xpress, I noticed it saying something about "Locking" my serial port,   
   enabling CTS/RTS flow control, and changing all of the speed entries in my   
   dialing directory to 38400 or 19200, how do I do this, and why should I?   
      
      Answer: In order to derive the enhanced throughput benefit offered by   
      
   --- MPost/2 v2.0a   
    * Origin: Marsh BBS (c) Dawson Creek BC Canada (1:17/23)