(ME = David Lesher)
> {lift CO from trunk port; put busy there..}
>
> Mike:
>
> It is the KSU and not the user that needs to know
> the line is busy. I can't think of any way to tell the
> KSU that a CO is busy other than to pick up a station
> associated directly with that CO.
> Charles:
>
> That device from Mike Sandman does work. www.sandman.com
> You have to be a bit clever with wiring it up, but it
> will do what you described.
>
>
> Me:
>
> What device from Sandman?
I was thinking of something like the MON4B loop sensing relay on this page.
http://www.sandman.com/wizard.html
However, I see it only has one form C contact, which isn't enough to do a
proper job. To do it right you need two form B or C
contacts (N.C.) to break T&R to the KSU when the direct device goes OH. You
also need one form A or C (N.O.) to pickup an extension
in order to busy out the CO line from the KSU's point of view. (Not sure how
well the KSU would tolerate a direct short on an analog
station port, so a resistance in series might be in order.)
To do this with the Sandman's relays, you'd need the MON4B and two MON4Es (or
some other suitable general purpose relay with enough
contacts). You'd also need an appropriate power supply for the AUX relay(s).
Gets pretty complicated and expensive.
This 'simple' solution has two flaws I can think of... You can still get into a
'glare' situation where both devices (e.g., modem
and KSU) attempt to seize the line simultaneously. Second, the direct device
has no way of knowing that the KSU has seized the line
and will butt in on the connection if asked to, cutting off the KSU caller. A
more complete solution would require yet another loop
relay to cut off the direct device when the KSU seizes the line.
I had worked this out at one point, when I was using dialup and found that the
modem would not connect at high speeds through my
KX-TD816. However, I switched to DSL and never actually build the device.
-Mike
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