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

Lawrence Katz larryka at gmail.com
Tue Feb 14 00:18:52 EST 2023


Hi Matt,

> I don't think a butt set and a tape recorder would be
> sufficient to record the audio which is about all I could
> possibly scratch up without spending money.

It's been a while since I've had to deal with POTS issues like you're
describing, but getting a recording off a buttset into a sound file (e.g.
WAV) that Audacity can handle was very useful back then. It would let me
analyze the duration and amplitude of the tones, as well as do frequency
analysis to make sure the tones were in spec. These days I might use some
of the blocks in GNURadio (it's not just for SDRs) to do further frequency
analysis.

This might give you some additional tools without spending money.

Hopefully this helps.

- Lawrence

On Mon, Feb 13, 2023, 14:16 Matthew Yaklin via VoiceOps <
voiceops at voiceops.org> wrote:

> Hello All,
>
> I guess I have an old school question for the list. The question is we are
> having trouble with alarm panels dialing and our gear collecting the DTMF
> digits properly. Only from a company ran by a single alarm panel guy who is
> not terribly helpful. At least 7 different sites are having the same
> problem on different copper pairs/T1s. Different gear. Etc...
>
> It seems we are always migrating off old DMS switches. In this case a DMS
> 100 with your typical line drawers with cards in them for pots lines or
> GR303 groups. We are migrating to a Metaswitch using different types of
> connections. In this case GR303 for some and SIP for others. ADTRAN gear in
> this case. TA4303 and a TA5000. We have been a Metaswitch shop for quite a
> long time now.
>
> Pretty vanilla stuff we rely on in many regions that has always "just
> worked" for legacy clients.
>
> Metaswitch -> GR303 to a TA4303 -> drop T1 to a TA3000 -> build a T1 on
> our copper plant -> Smart jack -> TA750 at customer location -> customer
> fire alarm panel
>
> Or...
>
> Metaswitch -> SIP -> TA5k with RPOTS cards in SIP mode -> copper plant ->
> demarc -> customer fire alarm panel
>
> What I am seeing is that the DMS was collecting the digits properly before
> the cutover. Yet our migrated to setup is having trouble. We see missing
> digits in most cases or other oddities. It does appear the alarm panels are
> dialing within DTMF specs. Duration of the DTMF is approx 95 ms. A DTMF
> signal separated by a 150-200 ms pause.
>
> Any other type of customer is working flawlessly. 100s and 100s of pots
> line migrated with no complaints except a single guy who manages fire alarm
> panels of a few different types. "Contact id Edwards". " Contact id ES4
> Kidde".
>
> Naturally, a tech sent on site can dial out fine with his butt set. The
> copper pairs test fine. T1 is error free. Hardware has been swapped out.
> Moved to different fxs ports. You name it we probably tried it.
>
> Does anyone have a suggestion what could be the cause for this? Something
> I am not aware of DMS wise when it came to fire alarm panels? Some change
> that can be adjusted in the fire panel configuration that might solve this?
> When we port/move the customer back to the DMS it just starts working again
> in the case of the TA5000. There is no going back for the GR303 subs which
> were moved all at once.
>
> Any tips are welcome!
>
> Thank you,
>
> Matt
>
>
>
>
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