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Philipp Kempgen wrote:
<blockquote cite="mid:4A686028.8030602@amooma.de" type="cite">
<pre wrap="">Steve Totaro schrieb:
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<pre wrap="">On Wed, Jul 22, 2009 at 12:07 PM, Steve Underwood <a class="moz-txt-link-rfc2396E" href="mailto:steveu@coppice.org"><steveu@coppice.org></a>wrote:
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<pre wrap="">Olivier wrote:
</pre>
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<pre wrap="">I've got a general question about analog gateways (Xorcom, Audiocodes,
Patton, ...) .
Is it usual for analog gateways to detect when an analog phone is
plugged in or out ?
If positive, would it be then useful to send "qualify" queries for
each connect phone (I'm implying here that an analog gateway would
then reply appropriately for qualify query.
</pre>
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<pre wrap="">Unless there is a call in progress the switch has no idea what phones
might be plugged or unplugged. Nothing happens on the line what it could
detect.
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<pre wrap=""><!---->
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<pre wrap="">It certainly would seem "possible" and would be a great feature request.
There probably is no circuitry existing to do it, but I would assume that
ohms, volts, or something could be measured while sending a small amount of
voltage down the FXS lines.
</pre>
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<pre wrap=""><!---->
Bonus point will be given for detecting the phone model and color
as well. ;-)
Philipp Kempgen
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Yes, it's technically possible for the phone company to determine if
there is a set or something connected to a phone line. It involved
hitting the line with +130v dc test voltage and reversing it quickly
and seeing how much capacatance kick there is. This kind of testing is
normal for telco CO lines. <br>
<br>
FXS chan units or gateways normally do NOT have this built into them.
The only exception I know about is SLC(Subscriber Line Concentrator,
which is a generiac term for fiber or digital lines feed to telco boxes
in the field). And even there the process was to have a cut-in relay
and connect the out cable pair back to the CO via a dedicated copper
pair to do these tests via a device called a PairGain Test Controller.
I know because I was an 'expert' on them and traveled around going from
telco CO to CO fixing them.<br>
<br>
In other words, there is some circuitry involved in doing these tests
and I don't see any PBX, FXS chan unit or gateway manufacturer rushing
to add more to this to their product line. They have not done it yet
and I don't see anyone other than the phone company willing to spend
the money to make it happen.<br>
<br>
To keep this on topic for Philipp's remark, the only bonus points we
assigned was to correctly guess how many phones were attached to the
phone line<GRIN>!<br>
<br>
Lyle Giese<br>
LCR Computer Services, Inc.<br>
<br>
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