DTMF detected only in-band?

[tjareson]

Hi,

 

does anyone know, what kind of DTMF-signaling IVM supports?

 

As far as I know, DTMF-keytones can be transmitted in-band, which means you really can here them in your hand set. The other way is, that those tones are decoded by VOIP-providers and transfered as "INFO"-format, which means, I don't here them.

 

I use IVM connected via Axon. One of my VOIP-providers encodes DTMF-signaling from in-band into INFO-format. So if I call myself by cell phone through this provider, I don't here those dtmf-tones in the hand set any longer.

The problem: Also IVM doesn't detect the DTMF-tones, if called through this line. I already talked to that VOIP-provider, which logged a call with dtmf-keys for me. They confirmed to me, that they don't transmit dtmf as in-band, only in "INFO"-format. They also stated, that the by "INFO"-format transmitted dtmf-keys are confirmed by the Axon software. So it seems, that IVM is not able to receive dtmf-tones, which are not in-band.

Does anybody know, how IVM detects dtmf?

 

May be, someone from NCH could comment on this.

 

regards

Tjareson

[polpolpol]

I have the same problem...

 

Maybe someone from NCH could comment on this?

 

thanks

sandro

[nchtj]

we support in-band and AVT (telephone events), but not INFO. INFO is an old-ish way of transmitting DTMF, AVT is the best standard out of the three.

 

in-band is often a very poor / dodgy way to transmit DTMF tones, because most VoIP systems use compressed codecs to transmit audio, in which case the tones also become compressed and may not sound like a proper tone by the time they get to the other end.

 

as far as INFO goes, we respond with a "501 Not Implemented", and thats it.