[SIPForum-discussion] No Ring Back Tone Issue

[Vivek Batra]

Comments inline in RED.

--VB

On Wed, Aug 27, 2008 at 9:23 AM, ramon nolasco <rpnolasco at yahoo.com> wrote:

> Hi All,
>
> Greetings and a good day to all of you! I have this and quite a rare one
> to me of "no ring back tone" problem with one of our interconnecting
> partners. Partner claims that our system normally sends "183 Session
> Progress" and "180 Ringing". That we are sending "183 Session Progress"
> without the ringtone data though our "180 Ringing" has a ringtone data. That
> their system looks for the ringtone data to process from the first received
> message response, which is our "183 Session Progress" and afterward
> disregards our "180 Ringing" response that followed, wherein the ringtone
> data is indeed present,  thus resulting to a successfull call but without
> ringback tone.
>
> My questions are, per standard:
>
>    1. When and why does "183 Session Progress" is being sent as a
>    response?
>
>  '183 Session Progress' or referred as Early Media is generally sent when
media (RTP) is required within early dialog.
Media is required in the early dialog when the call is placed from IP to
PSTN.
When ITSP/ Gateway routes the call from IP to PSTN, it generally sends the
183 response with SDP body and all the tones/ message are played by gateway
to UA. However in case of 180 Ringing, RBT is played by local UA itself.

>
>    1.
>    2. Should "183 Session Progress" sometimes also *can* replace "180
>    Ringing", thus have the ringtone data? or
>
> Yes. It depends on the local policy of UA whether it wants to stop the
media created with 183 Session Progress and start playing local RBT or
discards the 180 Ringing (recieved after 183 Session Progress) and remains
connect the media till the final response.
You will found lot of UA in the marked having both type of implementations.


>
>    1.
>    2. or it's always "180 Ringing" that has the ringtone data?
>
> I am not sure what you are referring as Ringtone data. I believe that you
are referring whether 180 Ringing has SDP or not.
If you are referring the same, my answer would be Yes. 180 Ringing can have
SDP body but this is not used to connect early media. 180 Ringing with SDP
refers the Offer-Answer model as per RFC 3262.
Only 183 Session Progress is sent as response to connect early media.

>
>    1.
>    2. Our setup is SBC-to-SBC, Huawei Eudemon 2300-to-Mediaring
>    Voizbridge, is it us who really has the problem or who needs then to adjust?
>    Adjust what?
>
> In the above statements, you are referring that 183 Session Progress has no
ringtone data. What actually you are referrig? You want to say that 183
Session Progress has no SDP?
Can you provide us the complete call flow?

>
>    1.
>    2. Is my partner's claim of "the should be system flow and process"
>    standard?
>
> Appreciate any of your solution advice and many thanks in advance :)
>
>
>
> Best regards,
>
>
>
> Mon
>
>
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