ISDN ALERTING vs PROGRESS on 183 Session Progress


When my asterisk receives a “SIP 180 Ringing” it sends to ISDN “Message Type: ALERTING (1)”.
When receives “SIP 183 Session Progress” it sends “Message Type: PROGRESS (3)”
It seems that the equipment connect to my Asterisk PRI doesn’t responds to “Message Type: PROGRESS (3)”, because the other side doesn’t hears any sound.

On sip trunk the early media is working because I see the RTP stream and confirmed that it has audio.
It’s possible to force asterisk to send “Message Type: ALERTING (1)” when it receives “SIP 180 Ringing” or “SIP 183 Session Progress”?
How can I do it?

David Costa

PTTs won’t generally respond to Progress from non-PTTs, because Progress allows one to provide a one way service without anyone being charged.

I believe the current versions of Asterisk (including 1.6.2) will not forward Progress unless you explicitly invoke Progress() in the dialplan, although you may need to explicitly invoke Ringing, if the far end doesn’t send it.

I think, therefore, that the answer is to upgrade.

I have upgrade my asterisk to version, but if the VoIP gateway sends “SIP 183 Session Progress”Asterisk pass “Message Type: PROGRESS (3)” to the isdn and my PBX doesn’t connect the audio.

So is the anyway of mapping “SIP 183 Session Progress” into ISDN “Message Type: ALERTING (1)”?

What I have:

-----SIP (183 Progress)-------| ASTERISK |------TDM (PROGRESS)------| PBX |

What I need:

-----SIP (183 Progress)-------| ASTERISK |------TDM (ALERTING)------| PBX |

If I force Ringing() in the dialplan, when I call a number that is disconnected, it works but with a little problem, that is hearing the ringing and then “This number isn’t available”


Change app_dial.c

You will still have the potential for calls that start with ringing but then fail, as Progress is used for things like voice announcements of failure.