Summary:ASTERISK-00486: DTMF outbound on i4l
Reporter:menger (menger)Labels:
Date Opened:2003-11-05 16:48:28.000-0600Date Closed:2011-06-07 14:11:53
Versions:Frequency of
Description:When dialing out to a remote IVR system from a SIP phone, pressing buttons does not generate DTMF tones on remote system.


I am using a NetJet-S card from traverse and i4l as the modem driver. I have disabled kernel DTMF detection and have asterisk doing the detection of DTMF tones. This works fine for incoming calls however on outgoing calls before and after this patch was applied, remote IVR systems can not detect me pressing buttons.

I ended up dialing my home phone and pressing buttons, no tone has been generated. However when i use sip to voicemail it works fine.

Is asterisk not generating DTMF tones on outbound i4l calls?
Comments:By: Paul Cadach (pcadach) 2003-11-06 21:37:43.000-0600

DTMFs can be transmitted in-band (as tones) and out-of-band (as informational messages at call control channel). So, check your i4l/asterisk configuration to pass DTMFs to ISDN as in-band, otherwise you will not hear them. As I can see, Asterisk passes all outgoing DTMFs as escape sequenses <DLE> <#DTMF> and this must be handled at your ISDN layer to generate real tone (but I don't found any code to generate inband DTMFs in the linux's ISDN drivers sources).

By: Brian West (bkw918) 2003-12-14 12:04:20.000-0600

If this is still an issue find me on IRC... irc.freenode.net #asterisk bkw_