[TriLUG] A Slow Serial Modem

[Joseph Mack NA3T]

On Sat, 21 Jan 2006, Brian Bell wrote:

>   1. does anyone have any experience in this area? ie. 
> connecting modern day stuff with 20+ year old equipment? 
> and/or any experience with this modem?

You should expect modems to handle all protocols back to day 
0. The other modem advertises what it can handle and your 
modern modem should fall into line.

However....

A friend had a security system at a remote location with a 
1200bd modem. The line dialing in was specified to be a 
particular brand/model modem of the same speed (why the 
security system specified the communications layer is beyond 
me). As any reasonable person would have done, he tried 
dialing in with a modern (56k) modem, but the 1200bd modem 
would not pick up. He solved the problem by buying the exact 
specified modem for his end through Ebay. Although I didn't 
know it at the time, the line he dialed out through also had 
DSL. The DSL was recently upgraded to some higher bandwidth 
(don't know, but about 10Mbps, it's optical to the house, 
which replaced copper) and now he finds that he can get the 
remote 1200bd modem to pick up with any modem he uses to 
dial in.

His problem then was the DSL although the filters are 
supposed to handle it. I have DSL and the people at the 
other end can tell something that the audio is hard to 
listen to. When I dial I get pumping noise. Presumably the 
modem can tell the DSL is there too.

He had some reason why he didn't want to substitute a modern 
modem at the remote site. I forget the reason.

Joe

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Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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