rmg@ultra.com (Rich Geiger) (07/11/90)
We recently installed two Telebit T2500's on the dailup lines into our
Unix system. We have noticed that some types of V.22bis modems (2400
bps) are having difficulties connecting at 2400bps when they dial in.
Based on various experiments, it appears that the T2500's V.32 answer
tones are being misinterpreted by some V.22bis modems; they seem to
respond to the V.32 tones rather than waiting for the T2500 to
downshift to the V.22bis tones. This seems to be a mariginal behavior;
with the afflicted modems, it will happen *most* of the time, but
occasionally they will wait for the coreect tones and get a proper
V.22bis connection.
I have tried adjusting the T2500's S92 register ("V.32 AC Transmit
Duration") down to the minimum (300 milliseconds), but that didn't
seem to make any difference.
If we disable V.32 on the Telebits, so that they answer directly with
V.22bis tones, the modems are always able to connect.
Calling modems that I have seen have the problem:
Everex Evercom 24+
Touchbase Systems Worldport 2400
Calling modems that I have never seen have the problem:
Everex 2400E
Practical Peripherals PM2400SA
Is this a known/common problem? Is unrealistic to expect that most
V.22bis modems will not be confused by the V.32 answer tones? Are
there any workarounds?
--
- Rich Geiger
Ultra Network Technologies / 101 Daggett Drive / San Jose CA 95134
rmg@ultra.com ...!ames!ultra!rmg (408) 922-0100 [w] (408) 739-7911 [h]max@phillo.SUBLINK.ORG (Massimo Gentilini) (07/18/90)
Mr. Rich Geiger on his message of 17 Jul 90 , says: RG> Everex Evercom 24+ RG> RG> Is this a known/common problem? Is unrealistic to expect that most RG> V.22bis modems will not be confused by the V.32 answer tones? Are RG> there any workarounds? Me too have a similar model and have a similar problem. I called Everex and they suggested me to put some commas after number, after a lot of trial and errors I ended with 18 commas after the number and it works great. IE to call my Usenet newsfeeder (that also uses a T2500) I compose the following: ATDP752697,,,,,,,,,,,,,,,,,, and it works fine. The problem arise also with HST Dual Standard (with HST and V32) but not with a Microcom modem (I don't remember the model) that have ONLY V32. Also with HST using commas works. Pratically you must put enough commas to avoid that your modem listen to the V32 tone.... Other V22bis that I have works well, other not, the only way to know is try it! Some days ago some people from Everex called me (wow!!! It was an Usa-Italy call, great service, I suppose) and promised me a new Eprom that cures this problem. If you want to call he gave me the following two number to call to report problems: 415-683-2662 415-438-4654 Ciao Ciao Massimo Gentilini -- E-Mail one of the following addresses: ****************************** UseNet: max@phillo.sublink.org * (2B) || !(2B) = ??? * FidoNet: 2:332/401 Bix: MaxGent ****************************** *** call my BBS at 0039-51-6343719, 2400 bps 24 hrs, 200Mb online ***
bourman@hpccc.HP.COM (BobbHewlett-PackardCorpNetEngPaloAltoCa.) (08/04/90)
You might want to check the "S" registers. You can increase the 'comma' pause time from the standard 2 seconds to what ever you program the appropriate "S" register to.