Linksys SPA3102 intermittent DTMF issue

[martinpluss]

Hi,
So on a customer site I have a UK BT PSTN line with a linksys SPA 3102 on it acting as a gateway to a 3CX PBX. Nothing new here - do it all the time.

However I am having issues with DTMF.

If I call the PSTN number using my mobile, my home landline, from a work handset on our ISDN - DTMF works as you'd expect within the digital receptionists - no problems there at all.

But..

If I call the PSTN number using a handset that goes out over OUR voip unlimited SIP trunk, DTMF detection on the customer site is intermittent at best and often doesn't work at all. There have been reports to the Customer from their customers that DTMF doesn't always work too, so its likely not just my handset/sip trunk provider combination here that suffers from the DTMF issue.

Any ideas? Any one seen this before?

 

[leejor]

Usually the DTMF issues, with the 3102, are the other direction.

What I suspect, since most incoming calls work just fine, is that DTMF tones sent via your VoIP provider are at either too low a level, too short a duration, or both.

About all you can try, and you risk echo problems, is to boost the incoming level.

PSTN Line/ International Control/ PSTN to SPA Gain

This default is 0 db, you can try increasing that, but, be aware that by doing so may cause other problems.

 

[eagle2]

You should send DTMF tones only by one of the available methods: inband, outband, DTMF info. Check your settings (probably the 3CX system, not the SPA itself.

Regards

 

[leejor]

Except, that this is incoming, analogue, from the PSTN line.