[SIPForum-discussion] No Ring Back Tone Issue
Herve Jourdain
herve.jourdain at mstarsemi.com
Thu Sep 4 09:08:00 UTC 2008
Hi,
I was not familiar with this RFC, so I had a quick look at it.
But it seems it doesn't entirely "leave out the SDP", even if it's "foggily
addressed" some times.
In 7.1.1 (En-bloc call setup), you can see some audio going on after a 18x
response. The comment says "This response may
contain SDP to establish an early media stream (as shown in the
diagram). If no SDP is present, the audio will be established in
both directions after step 8 >
This makes sense, and is already what has been discussed. Note the 18x. Step
8 is "200 OK".
The only place where 183 is explicitly used is when the call is rejected
with a reason, then 183 with SDP is specified (7.1.6 Cause present in ACM
message).
So basically, that sets Ramon back to the place where both solutions are
"legal" and SIP standard compliant, as 18x can be either 180 or 183.
And he'll have to work it out with his partner since both solutions seem SIP
compliant.
Thanks Anthony for pointing to this RFC I had overlooked, I must confess :-)
Regards,
Herve
_____
From: Anthony Orlando [mailto:avorlando at yahoo.com]
Sent: jeudi 4 septembre 2008 10:38
To: Herve Jourdain; SIP Forum
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
RFC3398 describes the inter-working yet it leaves out the sdp. My
experience is that we first receive 183sdp from early ACM then CPG which
maps to 180 w/o sdp. This casued our app server to provide ring tone as
well as the inband tone from the pstn.
Our appserver has a flag for this behaviour which the 180w/o sdp will not
trigger the ringtone to be provided by the media server.
Unfortunatley I have found that while RFC3398 and Q1912.5 describe the call
flows well they don't include sdp. This is an area that needs addressing.
--- On Thu, 9/4/08, Herve Jourdain <herve.jourdain at mstarsemi.com> wrote:
From: Herve Jourdain <herve.jourdain at mstarsemi.com>
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
To: "'ramon nolasco'" <rpnolasco at yahoo.com>, discussion at sipforum.org
Date: Thursday, September 4, 2008, 1:56 AM
Hi,
I can't remember a < normative > RFC that would state just that.
As far as I know, SDP and 18x handling is implementation dependant, though a
common use - that seems widely accepted - would be to have the SDP in 183
for ring back tone, when PSTN gateway is involved.
But again, this doesn't seem to me to be "normative".
And interoperability tests show that SDP can be sent both in 183 - most
common case - but also in 180 - happened with some switches. I even saw 183
responses without SDP.
In the end, for the playing of ring back tone, I decided to do it on both
180 and 183 messages, provided they had SDP inside, and generate local tone
if no SDP is provided. The background for this being that if anyone cares
enough to send some SDP, then it should be worth "listening" to it. But
again, this is an implementation choice.
So I'm not sure there is a "definite normative" answer to your problem, it
sounds like one - of many - SIP interoperability issue.
One of you or your partner will have to take some steps there. Your current
way is "legal" regarding SIP and your partner could handle it and still be
SIP compliant, and if you modify your behaviour to conform to what your
partner requires, you will also still be SIP compliant.
So to me, it sounds like you "just" need to make a decision about which way
you want to go with your partner, and implement it: you'll still be SIP
compliant either way.
My 2 cents: SDP in 183, again, seems to stick more to "common practices" in
SIP, in my opinion.
Hope this helps.
Regards,
Herve
_____
From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of ramon nolasco
Sent: mercredi 3 septembre 2008 03:21
To: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
Dear VB, Raghul, Cliff, Torstein, Vijay, Shyw13, Raghavendra and All,
Thanks and appreciate so much in sharing your know how, comments and tips,
which all are based on the existing standards and solid experience and
background.
One most important thing I need to clarify....
"As per standard, should our 183 response to the callee, SHOULD already have
SDP? For them then to play the ring back tone locally? Though we have the
SDP on our 180 response, but they can't consider processing it somehow"
Below is the email explanation of our partner on how their SIP system
handles our 183 and 180 responses. And with this, they wanted us to embed
SDP in our 183 message. Is their request to us still standard for SIP?
SIP Partner wrote:
With regarding on mentioned packet data SDP(Session Description Protocol
RFC2327) Yes, that should be the important keywords and necessary packet in
the sip connection for figure out this case .
We think following matter is the highlighted point which is complicating.
------------------------------------------------------------------------
1)
Our source device can accept the alerting message "only one time". but your
destination device didn't have SDP packet data when you advertise us the
"FIRST"alerting message.
That is why we couldn't realize the ring tone , even though your destination
device prepared the SDP packet data on the second exchange of alerting.
(Our source device cannot accept second contact for alerting from
destination device.)
2)
So ,we 'd like you to figure out the cause of missed SDP data on your first
alerting message.
We believe so that our source device can realize the ring tone sounds,
if we receive your SDP on your first contact for Alerting message.
------------------------------------------------------------------------
Point)
"Alerting message & SDP which you have prepared are correct", but our source
device need you to succeed it on the "the first time" of
alerting negotiation.
Sorry for my poor explanation , but i hope it can be your good help...
Thank you
I wish that you all say and comment, for it's in the standard, that SDP in
183 SHOULD NOT be the basis for playing the ring back tone for it's the SDP
in the 180 that SHOULD be the basis.
Regards,
Mon
----- Original Message ----
From: Torstein Knutsen <torstein.knutsen at gmail.com>
To: "WIGNELL, CLIFFORD (CLIFFORD)" <cwignell at alcatel-lucent.com>
Cc: discussion at sipforum.org
Sent: Friday, August 29, 2008 2:46:59 PM
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
Hi there
Beware that most operators do not allow early media as a default
configuration. Especially if you have an ISDN interconnect, it's not usual
enabled from the operators side. Meaning that "you" cannot send early media
back to the operaor.
Meaning that if a call flows trough your net like this :
(A-sub->PSTN->SBC1->...internet...->SBC2->PSTN->B-sub) Then early
media(ringtones, announcements etc) from B-subs "PSTN" will not reach A-subs
PSTN if SBC1's interconnect stops early-media...
regards
Torstein
On Fri, Aug 29, 2008 at 12:39 AM, WIGNELL, CLIFFORD (CLIFFORD) <
<mailto:cwignell at alcatel-lucent.com> cwignell at alcatel-lucent.com> wrote:
Hello Raghul,
Look at RFC3666, it describes the SIP<->PSTN call flows, by contrast RFC3665
provides "normal" SIP flows; good places to start.
Best regards
Cliff Wignell
_____
From: <mailto:discussion-bounces at sipforum.org>
discussion-bounces at sipforum.org [mailto:
<mailto:discussion-bounces at sipforum.org> discussion-bounces at sipforum.org] On
Behalf Of Raghul Prasanna
Sent: Friday, 29 August 2008 5:33 AM
To: Vivek Batra
Cc: <mailto:discussion at sipforum.org> discussion at sipforum.org
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
HI Vivek,
From your explanation I can understand that 183 with SDP result in early
media, but incase of 180 with or without SDP with no 183, will reult in UA
playing local ringback tone..
Just want to know is there any RFC that says the above point...
Thanks,
Raghul
--- On Wed, 27/8/08, Vivek Batra < <mailto:vivek7683 at gmail.com>
vivek7683 at gmail.com> wrote:
From: Vivek Batra < <mailto:vivek7683 at gmail.com> vivek7683 at gmail.com>
Subject: Re: [SIPForum-discussion] No Ring Back Tone Issue
To: "ramon nolasco" < <mailto:rpnolasco at yahoo.com> rpnolasco at yahoo.com>
Cc: <mailto:discussion at sipforum.org> discussion at sipforum.org
Date: Wednesday, 27 August, 2008, 4:09 PM
Comments inline in RED.
--VB
On Wed, Aug 27, 2008 at 9:23 AM, ramon nolasco <
<mailto:rpnolasco at yahoo.com> 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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