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

[Jay Hennigan]

On 2/13/23 11:48, Matthew Yaklin wrote:

> --- The issue is that when the alarm panel dials the INVITE from the TA5k does not contain the correct digits dialed. A couple of digits are missing for example. Sometimes a call does manage to squeak through properly. If the digits do get to the Metaswitch properly the call completes fine. Same exact symptom with GR303. In SAS (meta's service assurance server that contains debug output) I can clearly review what digits reach the metaswitch via GR303. In this case I will see missing digits as I know the number the alarm panel is supposed to dial and a gap of time which should have contained digits.

OK, so the FXS port of the local Adtran device isn't reliably decoding 
the DTMF from the panel. Could be frequency, level, or twist. See if 
there are knobs for receive level and/or impedance for the specific line 
port used by the panel. I'd start with level, bump it up and down 3dB at 
a time and see if it starts decoding reliably. If possible bracket it to 
see where it fails again and set it in the middle.

Changing impedance might help if it's twist. Sometimes the options 
include series capacitance. Likely going to be trial-and-error.

-- 
Jay Hennigan - jay at west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV