[SIPForum-discussion] No Ring Back Tone Issue

[杨伟]

Hi, all

I have a question about early media.

As Cliff has mentioned, 183 is sent by GW for early media establishment. My
question is ,if the 183 is not sent back by the GW, could early media such
as "The number you have dialed is not connected" be sent to the caller?

Because I think when the caller sent the Invite, it will hase SDP which
indicate the RTP address and port, the GW just sent the early media to this
address/port. Is this possible?




2008/8/28, WIGNELL, CLIFFORD (CLIFFORD) <cwignell at alcatel-lucent.com>:
>
>  Hi All,
>
>
>
> Just a comment on 183 vs 180,
>
>
>
> The reason early media is used when interconnecting with the PSTN/PLMN is
> that the backwards audio path can carry more information than just ringing,
> many times a call will be processed by a "Treatment" such as playing an
> announcement such as "The number you have dialed is not connected……". It is
> not normally the Gateway that plays these (MG) although it is possible to
> play announcements and tones form the MG, it is usually the Terminating PSTN
> Switch, but any Switch in the chain could potentially Treat the call. It's
> important to note that not all call Treatments end the call, there are such
> treatments as number interceptions where the announcement will be something
> like "The number you have dialed has been changed, the new number is……" and
> then the call is forwarded to the new number.
>
>
>
> Thus, in the case of a PSTN/PLMN you can't just play ringing from the UE,
> information may be lost.
>
>
>
> Best regards
>
>
>
> Cliff Wignell
>  ------------------------------
>
> *From:* discussion-bounces at sipforum.org [mailto:
> discussion-bounces at sipforum.org] *On Behalf Of *Vivek Batra
> *Sent:* Thursday, 28 August 2008 1:09 AM
> *To:* ramon nolasco
> *Cc:* discussion at sipforum.org
> *Subject:* Re: [SIPForum-discussion] No Ring Back Tone Issue
>
>
>
> 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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