[VoiceOps] Alarm panels and how they dial DTMF digits - pots migration from DMS to Metaswitch issue

[Matthew Yaklin]

If the DTMF digits used to set up the call are failing, then there's likely something out of spec with the DTMF encoders in the alarm panels, frequency or twist. Or something different in the call setup like a leading 9 for a PBX that no longer exists. What does the sending Adtran show for the dialed digits on the call?


--- An example would be the fire alarm panel should dial 877-386-4923. Yet we collect the digits on the Metaswitch as 877-38923. That is it. The 6 and 4 are missing. The Metaswitch dial-plan times out and it tries to process those digits and the call fails. There is a gap of time of approx 600 ms where the Metaswitch does not collect anything and according to the time pattern should have been the 6 and 4. On top of that this is over GR303 with no SIP involved. Good old fashioned analog pots lines with TDM T1 circuits to the Metaswitch. Very old fashioned. Also in this example the TA750 channel bank is located at the customer premise with the alarm panel only 300 feet away.

--- It is truly a mystery to me. Short of using specialized gear and spending countless hours to find the blame I am out of ideas. This very same setup works for many other fire alarm panels. The gear used to provide the clients pots lines is the same exact gear that used to be hooked up to the DMS 100. We just configured a gr303 sub on the meta, built new gr303 T1s to the TA4303 from the meta, and ported the TN. Nothing else changed. I have done this type of migration for tens of thousands of pots lines from a DMS to the meta. First time I ran into this over all these years.


Matt