[SIPForum-discussion] No Ring Back Tone Issue

Thu Aug 28 17:45:08 UTC 2008

Answer of 1---->

SIP 180 and 183 (media) message to ISUP ACM message

*The existing 180 Ringing message would indicate that
   the calling user agent has the option of providing local alerting
   (and generally should).  *

* *

*The 183 Session Progress message would indicate that the calling user
agent should not provide local alerting.*

* *

* *

*The indication of whether or not to play early media to the*

*   calling user would be controlled with a new Session header included*

*   in the 183 message.*

2008/8/28 杨伟 <shyw13 at gmail.com>

> 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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>
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