Problems with DTMF recognition via IAX channel


#1

Hello,

I subscribe to the Voicepulse connect service, which gives me a PSTN interface via IAX. When callers are greeted by the IVR system, their DTMF tones are not always recognized. I’ve tried various codecs, but none of them make any difference.

SIP has the relaxdtmf switch, is there something similar for IAX?


#2

DTMF is always out of band for IAX.

Do an iax2 debug from the CLI and see if the codes are coming though.

I’ve experienced the same problem.

Asterisk seems to have a problem when jitterbuffer is used on IAX. DTMF codes are comming through, but when jitterbuffer is on, it is unpredictable if Asterisk will notice the codes coming in. When I shut off the jitterbuffer the problem goes away, and the nasty sound of jitter rears it’s head.

I’ve posted a bug report on the issue tracker but no one seems to be looking at the problem.

I really can’t believe this is a rare problem. I’ve seen it on three different builds of Asterisk now.


#3

i’ve noticed that muting the phone’s mic (difficult to do on a customer’s analog phone, i know) often results in better DTMF recognition.

does voicepulse offer SIP? i’m no expert, but sometimes i’ve had better luck with SIP than IAX in the sound quality area. even if you’re behind NAT, you might want to give SIP a shot.