DTMF Digit Loss Over High Latency Connection

Unanswered Question
Mar 19th, 2009

We have a problem where when our remote analog phones dial to a PSTN telco which requires DTMF to be entered,

some DTMF tones are skipped and the call would not proceed correctly. We did a debug on the VG224 and the PSTN gateway

and found that when the VG224 receives the DTMF digits from the MUX, it missed two out of the 14 DTMF dones. So it is not the PSTN gateway issue.

Would anyone know any of the FXS port configurations that would enhance the DTMF digits? We did try the gain, attenuation, timer digits to no success.

Apprecaite any help, comment and advice. Thanks.

It is a complicated setup so thanks for your patience!

Here is our current setup:

Telco IVR<-->PSTN<-->MGCP GW<-->IPT<-->SCCP VG224 FXS<->MUX<-->Satellite<-->Mux<-->Remote Analog Phone

We have confirmed the following works:

- IP phones dialing to PSTN incoming outgoing - ok

- IP phones dialing to Telco IVR - DTMF ok

- Analog phone connected to VG224 to PSTN incoming outgoing - ok

- Analog phone connected to VG224 to Telco IVR - DTMF ok

- Remote Analog phone connected to MUX to PSTN incoming ougoing - ok

Problem: Remote Analog phone connected to MUX to Telco IVR - Fail. DTMF digits not passed correctly.

P.s: we are using CUCM6.1(2). VG224 is using 12.4(22)T. MUX brand is Verso.

Thanks!

A

I have this problem too.
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paul_savage Mon, 07/12/2010 - 02:01

Hi..

Did you manage to resolve you issue and if so, would it be possible for you to relay your findings ?

I have similar issue, but with FXS ports on 887 VG as SIP.  Proxy server is located in Portugal and the call setup times are dreadful, so have played with timers etc...

my issue is that DTMF 2 is not being passed properly or not at all...this is affecting door entry systems for some reason, standard analogue BT phone works fine...... go figure...

thanks in advance and if you have any insights I would greatly appreciate..

regards

Paul

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