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VG248 and Fire Alarm Company


Problem with VG248 and Fire Alarm Company. Call is made by Fire Panel. Once the Call is established it send a fire code to Provider. The call goes through but the call drops when codes are sent. Alarm company is saying that the line must be a traditional pots line. Any help would be appreciated.

7 Replies 7

Rob Huffman
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Hall of Fame Community Legend

Hi Roy,

In my experience with the VG248 I would say that the lines should be able to do anything that a POTS line is capable of. When the call is established you said that codes are sent, can you tell us if this means a sequence of DTMF tones or something else? Are there any Hookflashes involved? Perhaps it is something to do with the "Call Control Mode".Check out this link to see if it helps:

Let us know in a bit more detail exactly what is happening and I'm sure someone here will be able to help you out.

Hope this helps!


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I have the same problem as well, with the VG248 and Alarm Company.

Did you manage to fix the issue?



We had the same problem and TAC could not help. We finaly gave up and put in traditional pots lines. This is also incase the phone system or pri curcuits are down we still have conectivity. Good luck.


Hi Steve,

Thanks for the response, in my case the Alarm Company monitors residents in aged care facility.

There are 3  x VG248 for the resident phones, the phones have emergency capability that send DTMF Codes to the alarm monitoring company, the alarm company uses these DTMF codes to identify the room numbers, alarm type and Person who triggered the alarm.

Replacing it with traditional pots will be expensive solution. Will VG224 work?

I heard from a friend the issue is related to the DTMF sample size used by VG248, default 100ms.

Could it be related to the DTMF sample size??? Thanks for your help.




Did anyone ever resolve this issue?  We are having the same problem.  Out fire alarm panels used to be fax type tones, they now use DTMF tones and will not work with the VG248 or 224.


We ended up having to put in a traditional pots line for this particular site.

Thank you,



From memory we ended up fixing the issue, In our case the issue was the duration of the DTMF tones. The DTMF tones sent by the Cisco equipment to the monitoring company was fast, monitoring company was not able to catch all the tones. Adjusting the duration on the Service parameter resolved the issue. The ISDN Gateway was H.323. What is your voice gateways protocol , MGCP or H323?

Hope this helps



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