marx@VMS.HUJI.AC.IL (Michael M. Marx / Jerusalem - Israel) (11/08/90)
Hi Folks, I was wondering, Is there a company that manufactures PASSIVE modem? When I say Passive modem I mean a modem that does not broadcast at all, only receive, this is useful for a third party to listen to the other two parties without making things messy. to make a long story short. A and B are speaking, C wants to hear, but C can't do that with a normal modem since a normal modem will respond to received broadcast. I want C only to listen . Thanks for replies. Michael. +------------------------------------------------------------------------------+ Michael M. Marx marx@vms.huji.ac.il / marx@hujivms.bitnet The HUJI, Jerusalem. "You only live for 2207520000 seconds, Israel so make the best out of them!" - M. M. Marx +------------------------------------------------------------------------------+
bill@bilver.UUCP (Bill Vermillion) (11/12/90)
In article <457@shum.huji.ac.il> marx@vms.huji.ac.il writes: >Is there a company that manufactures PASSIVE modem? >When I say Passive modem I mean a modem that does not broadcast at all, only >receive, this is useful for a third party to listen to the other two parties >without making things messy. >to make a long story short. >A and B are speaking, C wants to hear, but C can't do that with a normal modem >since a normal modem will respond to received broadcast. I want C only to listen. C can't do that with a normal modem, if you mean the old style modem that had no "smarts" as all. If you have a "hayes" command set compatible modem set register C to 0 to turn off the transmitter, then set S10 to 255 to ignore carrier status and stay on line all the time, then a D or an A depending on which side of the line you wish to monitor. You need to monitor the side doing the echoing so you can see what it sent, and what the other side transmitted. -- Bill Vermillion - UUCP: uunet!tarpit!bilver!bill : bill@bilver.UUCP
marx@VMS.HUJI.AC.IL (Michael M. Marx) (11/18/90)
In article <1335@bilver.UUCP>, bill@bilver.UUCP (Bill Vermillion) writes... >In article <457@shum.huji.ac.il> marx@vms.huji.ac.il writes: >>Is there a company that manufactures PASSIVE modem? >>When I say Passive modem I mean a modem that does not broadcast at all, only >>receive, this is useful for a third party to listen to the other two parties >>without making things messy. >>to make a long story short. >>A and B are speaking, C wants to hear, but C can't do that with a normal modem >>since a normal modem will respond to received broadcast. I want C only to list en. > >C can't do that with a normal modem, if you mean the old style modem that >had no "smarts" as all. > >If you have a "hayes" command set compatible modem set register C to 0 to >turn off the transmitter, then set S10 to 255 to ignore carrier status and >stay on line all the time, then a D or an A depending on which side of the >line you wish to monitor. You need to monitor the side doing the echoing >so you can see what it sent, and what the other side transmitted. Still, Something is missing, you need some string in order to disable to handshaking "desire" of this modem, naturally, the modem wants to coordinate with the other modems, and this desire must be opressed somehow... -Michael +------------------------------------------------------------------------------+ Michael M. Marx marx@vms.huji.ac.il / marx@hujivms.bitnet The HUJI, Jerusalem. "Your mission, should you decide to accept Israel it will be..." - Mission: Impossible +------------------------------------------------------------------------------+
alexis@panix.uucp (Alexis Rosen) (11/18/90)
I have no interest in this topic myself but a few days ago I noticed that
my 2 or 3 year old US Robotics 2400e has exactly this feature. Call them
if you want more info- I don't know anything about it...
---
Alexis Rosen
Owner/Sysadmin, PANIX Public Access Unix, NY
{cmcl2,apple}!panix!alexisbill@bilver.UUCP (Bill Vermillion) (11/22/90)
In article <493@shum.huji.ac.il-> marx@vms.huji.ac.il writes:
->In article <1335@bilver.UUCP>, bill@bilver.UUCP (Bill Vermillion) writes...
(all the part about needing/wanting to monitor a line with another
modem deleted - I'm just responding to what I wrote - bill)
->>If you have a "hayes" command set compatible modem set register C to 0 to
->>turn off the transmitter, then set S10 to 255 to ignore carrier status and
->>stay on line all the time, then a D or an A depending on which side of the
->>line you wish to monitor. You need to monitor the side doing the echoing
->>so you can see what it sent, and what the other side transmitted.
->Still, Something is missing, you need some string in order to disable
->to handshaking "desire" of this modem, naturally, the modem wants to
->coordinate with the other modems, and this desire must be opressed somehow...
Nothing is missing. Read your manual. Set register C to 0 and the
transmit side will be turned off. It will then be a receive only modem.
Set register 10 to 255. That will totally ignore carrier, so it will just
sit and listen forever (or until you turn it off).
(Is that what you are talking about the "desire".)
Then by issuing the A or D, you turn the modem receiver to what part of the
line you wish to listen to, the transmit or the receive.
(Or is this what you mean by the "desire". "desire" is not a standard
modem term ;-} .
If you are wanting to monitor both sides of a full-duplex connection,
monitor the signal that is coming FROM the unit doing the echoing.
The only thing that won't show are things where echoing is turned off, eg
password entry, and the like. If you monitor the other side of the line the
only thing you will get is what is transmitted to the host.
If you don't have a Hayes Brand modem, read the descriptions of the
registers described. If you have a genuine Hayes, look in the manual and
you can even see a diagram. It's in Appendix G of 1982 manual for the 1200
Smartmodem. I paid about $550 for that modem discounted. (Yes Larry,
that's the one I bought from you!). Things have surely gotten cheaper ;-)
--
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
: bill@bilver.UUCPgws@cbnews.att.com (Gary W. Sanders) (11/28/90)
In article <457@shum.huji.ac.il>, marx@VMS.HUJI.AC.IL (Michael M. Marx / Jerusalem - Israel) writes: > Hi Folks, > I was wondering, > Is there a company that manufactures PASSIVE modem? > When I say Passive modem I mean a modem that does not broadcast at all, only The US robotics courier 2400 will let you turn off the transmitter and listen to two other modem talking. Not sure if other modems will permit this or not. -- Gary Sanders (N8EMR) AT&T Bell Labs, Columbus Ohio gws@cblph.att.com 614-860-5965