[asterisk-users] DTMF problem

[Olle E. Johansson]

19 sep 2011 kl. 01:51 skrev Zeeshan A Zakaria:

> This DTMF problem has always been there and there is no real solution for it, other than using those expensive PBX systems like that from Avaya, Cisco, etc. This problem happens when you are sending inband DTMF tones. Via softphone you are sending out-of-band DTMF which is basically SIP messages.

Just to correct the latest part of your statement:

The default way to send DTMF in SIP calls is using DTMF as a codec called telephony-event in the RTP stream. This sends DTMF as events. Most hard and soft phones support this - usually called RFC2833 DTMF mode. Asterisk supports it by default. 

Sending DTMF in the audio usually gets messy when using an IP network. Especially if you use codecs that compress the audio. I do recommend you to use RFC2833. We have built very large IVR services and have no issues with DTMF being received in Asterisk so it's doable.

There are other issues with Asterisk DTMF, but that's another issue :-)

/O