Two modems on one telephone line

Two modems on one telephone line

Post by Dan McAllist » Thu, 18 Jan 1996 04:00:00




> Mabe somebody can help me. I want connect two modems and I can't use
> telephone line. ( No I can use it but I can't choose telephone numbers
> beacouse I bouth modems I have in my house , and I have only one telephone
> line.). I know that I can connect computers by Null Modem , that mean by
> RS  without modems but I must use modems. How modem work at lease lines?

I apologise if this answers the wrong question, but here goes:

Most "dial" modems don't require much from the phone line, so it is possible
to connect them simply by connecting them with a regular phone "extension"
line (i.e. RJ11 adapter on both ends of one line).  The trick then is to fool
the modems into thinking there's a CO between them.

On one side, strap the modem to IGNORE dial-tone (that is: do NOT detect dial
tone).  On our KIT 3.0 modems, this would be an X0, X1, or X3 command.

Now tell this modem to dial any digit (e.g. ATD1)... immediately after this,
go to the other modem and enter the answer command (e.g. ATA).  The modems
should train right up (they do here in our lab and do for me at home
frequently).

NOTE: This method will NOT work with modems that use AT&T's OLI DAA (Optical
Line Interface) for reasons that should be obvious, but that I won't go into
here.

Hope this helps (you and the dozens of others who have asked over the past
several months)

Dan
=================================================
Dan McAllister, Consultant Firmware Engineer
AT&T Paradyne / Wireless Technology


 
 
 

1. Two modems on one telephone line

Mabe somebody can help me. I want connect two modems and I can't use
telephone line. ( No I can use it but I can't choose telephone numbers
beacouse I bouth modems I have in my house , and I have only one telephone
line.). I know that I can connect computers by Null Modem , that mean by
RS  without modems but I must use modems. How modem work at lease lines?

                                Lukasz Dutka

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