[Freeswitch-dev] Session Progress and RINGING

Thu Nov 4 14:29:42 PDT 2010

Hi,

yes, they are not really sure but I think that the given RFC does specify this correctly (this does not mean, that all the SIP devices work like that). I could understand that a change will maybe result in big troubles. Perhaps a option for mod_sofia to "support-rfc3960" would be a good solution. If you want I will write the patch because it should be "really simple" to ignore the CF_EARLY_MEDIA if the option is set, or?

We get the Session Progress with SDP and later the 180 Ringing from a session border controller (I am not 100% sure, but I think its a a Audiocodes).  The 180 Ringing has to be sent towards A because A is a ISDN gateway.

Would do you prefer? Thanks for your investigation.

Best regards,
Bernhard Suttner

----- Original Message -----
From: Anthony Minessale [mailto:anthony.minessale at gmail.com]
To: freeswitch-dev at lists.freeswitch.org
Sent: Thu, 04 Nov 2010 22:09:48 +0100
Subject: Re: [Freeswitch-dev] Session Progress and RINGING

> My conclusion from reading that discussion is they have no idea what to do.
> There are votes both ways and 2 attempts to go of onto a tangent into
> another topic.
> 
> We have chosen on our implementation to ignore 180 once we have
> already established a media path from a 183.  The RFC is just vague
> enough that this decision falls to us.
> 
> I understand that ISDN has more precise signaling in this regard.
> PROGRESS or ALERTING both with or without media as a flag on the packet.
> 
> But the vast majority of SIP devices in the wild will ignore the 180
> once early media has been established.
> So even if we make changes to support this, it will be ignored by the
> next guy in line.
> 
> Do you hear media during this early media phase?
> 
> This is why we have the originate param
> {ignore_early_media=ring_ready} which will, in the case of sip,
> translate 183 or 180 with and without SDP into a 180
> 
> To change it to do what you are asking for could have extreme negative
> side effects and not even work in most devices so this is why I am
> reluctant to change it.
> 
> Are you trying to cross connect 2 ISDN lines over SIP and preserve the
> signalling?
> If so, this is why SIP is flawed to begin with because it is lossy in
> telephony signaling data.
> This is why they now try to embed ss7 messages in the sip packets. =p
> 
> 
> 
> On Thu, Nov 4, 2010 at 3:51 PM, Bernhard Suttner
> <bernhard.suttner at winet.ch> wrote:
> > Hi,
> >
> > session progress does have SDP which will then go through to A. But on the
> display of A it will only display "session progress" and not Ringing. If A
> is now a ISDN Gateway and has to signalize RINGING into the "ISDN world". I
> am not sure, if RINGING will be used for A to generate the ringback tone for
> itself on every device. This behaves on the client/device configuration.
> >
> > There was a nice discussion about this "issue" on the sip-implementors
> list:
> >
> >
> http://www.mail-archive.com/sip-implementors@lists.cs.columbia.edu/msg06400.html
> >
> > There is a RFC for this case (Section: 3.2.  Ringing Tone Generation)
> > http://www.rfc-editor.org/rfc/rfc3960.txt
> >
> > What do you think?
> >
> > Best regards,
> > Bernhard Suttner
> >
> >
> >
> > ----- Original Message -----
> > From: Anthony Minessale [mailto:anthony.minessale at gmail.com]
> > To: freeswitch-dev at lists.freeswitch.org
> > Sent: Thu, 04 Nov 2010 16:54:30 +0100
> > Subject: Re: [Freeswitch-dev] Session Progress and RINGING
> >
> >
> >> no, once it gets session progress it will not send any ringing.
> >> The sip side 180 ringing is used to tell the phone to generate its own
> >> inband ringing.
> >>
> >> does your 183 session progress contain a sdp?
> >>
> >>
> >> On Thu, Nov 4, 2010 at 10:25 AM, Bernhard Suttner
> >> <bernhard.suttner at winet.ch> wrote:
> >> > Hi,
> >> >
> >> > A ---> FS ---> B
> >> >
> >> > B does send a Session Progress to FS. FS will forward the Session
> Progress
> >> to A.
> >> > B does send a RINGING to FS. FS does _not_ forward this to A.
> >> >
> >> > Could it be, that the check the switch_test_flag(channel,
> CF_EARLY_MEDIA)
> >> in mod_sofia.c within the INDICATE_RINGING section is wrong. I think it
> is
> >> allowed to send the Session Progress first and later the RINGING. The
> >> ringing is for example for SIP/ISDN gateways necessary.
> >> >
> >> > Any hint is appreciated.
> >> >
> >> > Best regards,
> >> > Bernhard Suttner
> >> >
> >> >
> >> >
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> >> >
> >>
> >>
> >>
> >> --
> >> Anthony Minessale II
> >>
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> 
> 
> -- 
> Anthony Minessale II
> 
> FreeSWITCH http://www.freeswitch.org/
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> Twitter: http://twitter.com/FreeSWITCH_wire
> 
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> MSN:anthony_minessale at hotmail.com
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> 
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> 
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