I have the problem of "no ringback".
The scenario is:
1. A sip phone (Grandstream BT201)
2. Yate (latest from svn)
3. Public ISDN network via Sangoma A108
4. Called phone
My SIP Phone sends the INVITE to YATE that reply with a 100 trying.
Yate sends a SETUP message to PSTN via ISDN E1 connection.
PSTN sends a CALL PROCEEDING
PSTN sends an ALERT message
YATE sends a 180 Alerting with SDP to caller Phone
In this situation I don't ear the ring tone because the caller phone has received the SDP in 180 ringing but the ISDN audio path is not yet closed.
But why Yate sends the SDP message? The SDP message shouldn't be related to ISDN "media"?
In the ISDN side the media is present after CONNECT message or when CALL PROCEEDING, ALERT or PROGESS is received with an appopriate (ie. in-band-info) progress description information element.
Another question: the q931.cpp file in the "processMsgCallProceeding" method and in the "processMsgAlerting" method seems to ignore the information element Progress Description that can contains essential info (i.e. in-band-info). I'm wrong?
Protocol discriminator: Q.931
Call reference value length: 2
Call reference flag: Message sent to originating side
Call reference value: 0012
Message type: ALERTING (0x01)
SIP 180 Ringing:
Session Initiation Protocol
Status-Line: SIP/2.0 180 Ringing
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): yate 1277387718 1277387718 IN IP4 -----------
Session Name (s): SIP Call
Connection Information (c): IN IP4 ---------
Time Description, active time (t): 0 0
Media Description, name and address (m): audio 27108 RTP/AVP 18 101
Media Attribute (a): rtpmap:18 G729/8000
Media Attribute (a): fmtp:18 annexb=no
Media Attribute (a): rtpmap:101 telephone-event/8000