Home alarm system

Hi all,

I have been using FreePBX for many years now, and it’s working great. I was using only a voip.ms trunk but lately, I changed changed my home phone system (not voip.ms) for an IP telephony service offered by my telephony company. So I have now two trunks, and all my calls goes thrun the new trunk with my telephony company. It all work very well.

The problem I have, is with my home alarm system that tries to make call every morning to make sure it can communicate with the alarm central company. The alarm system makes the call, I see it pass thru my FreePBX, and the few first attempt the call is answered, last for about 20 seconds, then it hang-up, and retries a couple of time. At the end, the home alarm system starts “beeping” to tell me that there is a communication problem.

Anyone had this problem and got a clue on how to solve it ?

The alarm company, tells me that they cannot do nothing, and that I need to install their “Internet system” (250 $ !!!) to allow the communication with their system via Internet, instead of via the phone calls.

VOIP and modem systems do not mix well, try making your codec G711, that might make things better.

Thank you for your answer.

I have looked in FreePBX -> Tools ->Asterisk SIP settings, and the g711 codec does not appera there. How can I activate that codec and, I guess that I should also put it in my extension config ?



I would really recommend not to do this. Most central station contracts don’t allow it and do hou really want your house burning down becuase your voip system was screwed up?

My alarm company provided me a witha GSM modem and it ends up costin under 10/mo for the SIM


I have no affiliation with this company except as a customer. Their solutions only work with alarm systems which use the “Contact ID” protocol. If you are in the United States and your alarm system is less than 10 years old, there is a fairly good chance that it uses Contact ID.

Depending on your specific alarm system, there may be other possibilities which cost less than $250. For example, if you have a DSC alarm system, it can probably be upgraded with DSC’s TL150 option board ($200+ if you buy it from a professional installer/dealer), but there are other companies who make TL150-compatible boards such as http://eyez-on.com/EZMAIN/ip100d.php ($100 to buy online and install yourself, and it offers more features). Compatible means that it is the exact same size as TL150, uses the exact same wiring, and communicates with the main board exactly like TL150.

You should be connecting the alarm system to an FXO adapter. Make sure in its configuration you allow only G711 codec (ULAW).

In freepbx you can edit the extension configuration. There is an inputbox for Disallow and another for Allow. Try disallowing all and allowing ulaw.

This is the only you can do in your Asterisk. The other problem is the provider transport protocol. They often uses G729 that is a very good codec for voice but it is loosy, then modem or faxes often fails.

You can try forcing the use of G711 in the trunk if your provider allows it (disallow=all allow=ulaw), but it uses more bandwidth.

Transporting data over a voice link that is packed inside a data link is not a good idea.