This is a very big headache for me.
Alarms today normally use a protocol called contactID for
communications. These are very short dtmf tones and most devices have
a very hard time transmitting them. also any jitter etc causes them
to be unreadable. If anyone has a reliable method for transporting
across an IP net I would like to hear about it.
The only solution I have found, and the manufacturers seem to agree
is to not use contactid. Most central alram stations support a couple
others. One would be SIA and the other is something like '4of7'
Most though are contactid by default and that is all some can do. It
seems to pass more descriptive info of the alrams vs the other
methods but the others do work.
On Dec 17, 2005, at 10:31 AM, Rich Adamson wrote:
I am trying to get some feedback from anyone who may have
experience of
a problem I am having.
We have several buildings that having only fiber to them so in order
that the alarm panel can call the central station, I have provided a
Sipura 1001 ATA. I can make a call to the central station through the
ATA, using an analogue phone.
The alarm panel does not seem to function properly thorugh the ATA,
either it is not going off-hook properly or the ATA is treating the
modem tones as a fax, I am not sure what is happening. Does anyone
have
experience of getting this to work?
Is the alarm panel truly expecting to use a modem to communicate with
central station?
If so, sip/rtp will not handle modems that attempt to use anything
greater then about 2400 baud. (Note: there is a diffence is the term
"baud" verses "bits/second". Newer high-speed modems use an encoding
mechansim that involves phase-shift technology to achive a higher
bit-per-second speed over a low baud rate. sip/rtp will not accurately
reproduce any modem signal that involves phase-shifting. The sampling
rate is not sufficient to accurately reproduce phase-shifted analog
signals.)
Also, in the sipura release notes (for v3.1.5) specifically
indicates they watch for fax tones and, more recently, modem tones.
. Distinguish between FAX Passthrough mode and Modem Passthrough
Mode.
Modem Passthrough Mode can only be triggered by predialing the
<Modem Line Toggle Code>. FAX Passthrough Mode is triggered by
CED/CNG tone or NSE events. Echo canceller is automatically
disabled
for Modem Passthrough Mode only. Echo canceller is
automatically disabled
only if <FAX Disable ECAN> (Line 1/2) is set to "yes" for that
line
(in that case FAX passthrough is the same as Modem passthrough).
Call-waiting and silence suppression is automatically disabled
for
both FAX and Modem passthrough as before. In addition, out-of-
band
DTMF Tx is disabled during modem or fax passthrough (all audio
are
The "Modem Line Toggle Code:" option appears on the Regional tab and
has a default string of "*99". Therefore, your alarm panel modem would
need to prefix its dialing with *99.
Might check those two items.
Rich
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