[SIPForum-discussion] P-Early-Media and Offer-Answer Relation
Vijay Kumar
vj.tech776 at gmail.com
Thu Jun 20 06:17:03 UTC 2013
Hi as per 3261
If the initial offer is in an INVITE, the answer MUST be in a
reliable non-failure message from UAS back to UAC which is
correlated to that INVITE. For this specification, that is
only the final 2xx response to that INVITE. That same exact
answer MAY also be placed in any provisional responses sent
prior to the answer. The UAC MUST treat the first session
description it receives as the answer, a*nd MUST ignore any*
* session descriptions in subsequent responses to the initial*
* INVITE.*
*
*
I feel that even the SDP in 18x and 200 Ok are (changed in version)
different it must be ignored and call must not be droped
Regards
Vijay
On Wed, Jun 19, 2013 at 9:30 PM, <discussion-request at sipforum.org> wrote:
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> Today's Topics:
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> 1. Sdp attribute for Call hold (ankur bansal)
> 2. Re: P-Early-Media and Offer-Answer Relation (tarun patta)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 19 Jun 2013 11:26:02 +0530
> From: ankur bansal <abh.ankur at gmail.com>
> Subject: [SIPForum-discussion] Sdp attribute for Call hold
> To: "discussion at sipforum.org" <discussion at sipforum.org>
> Message-ID:
> <CA+22TkCmM78Z9hFBxThwuiGRhfHyTOOPfJEROXu01Mm1n=
> g+_g at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi All
>
> Can anyone explain why a=sendonly is sent in offer from side performing
> HOLD ?
> I think a=inactive should be right way of holding call .
> Any specific scenario which explain when to use sendonly and when inactive
>
> Thanks & regards
> Ankur Bansal
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> ------------------------------
>
> Message: 2
> Date: Tue, 18 Jun 2013 14:26:20 -0700 (PDT)
> From: tarun patta <tkp866 at yahoo.com>
> Subject: Re: [SIPForum-discussion] P-Early-Media and Offer-Answer
> Relation
> To: Stephen James <sjames_1958 at yahoo.com>, Pranav Damele
> <pranavdamele at gmail.com>, ankur bansal <abh.ankur at gmail.com>
> Cc: "discussion at sipforum.org" <discussion at sipforum.org>
> Message-ID:
> <1371590780.2872.YahooMailNeo at web164906.mail.bf1.yahoo.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hello All,
>
> As ?per (rfc3264)
> http://www.ietf.org/rfc/rfc3264.txt
>
> Nearly all aspects of the session can be modified. New streams canbe
> added, existing streams can be deleted, and parameters of existing
> streams can change. When issuing an offer that modifies the session, the
> "o=" line of the new SDP MUST be identical to that in the previous SDP,
> except that the version in the origin field MUST increment by one from the
> previous SDP. If the version in the origin line does not increment, the
> SDP MUST be identical to the SDP with that version number. The answerer
> MUST be prepared to receive an offer that contains SDP with a version that
> has not changed; this is effectively a no-op. However, the answerer MUST
> generate a valid answer (which MAY be the same as the previous SDP from the
> answerer, or MAY be different)
> As per Ankur, the SDP coming in 183 and 200 is same so version number
> should not change, I agree with Stephen?that the call will disconnect if
> you or your vendor is having an Ericsson switch.
>
> Regards
>
>
> T.K.Patta
>
>
> ________________________________
> From: Stephen James <sjames_1958 at yahoo.com>
> To: Pranav Damele <pranavdamele at gmail.com>; ankur bansal <
> abh.ankur at gmail.com>
> Cc: "discussion at sipforum.org" <discussion at sipforum.org>
> Sent: Saturday, June 15, 2013 11:13 AM
> Subject: Re: [SIPForum-discussion] P-Early-Media and Offer-Answer Relation
>
>
>
> Read - http://tools.ietf.org/html/rfc6337
> This indicates that if the 183 is not reliable, then the offer/answer is
> not complete until the reliable (200 OK, or 18x w/ 100rel) is received.
> There is some confusion in that the spec says that the UAC should treat
> the 183 SDP as a preview of the final answer and that it should not change
> in the 200 OK.
> RFC 3261 says:
>
>
> If the initial offer is in an INVITE, the answer MUST be in a reliable
> non-failure message from UAS back to UAC which is correlated to that
> INVITE. For this specification, that is only the final 2xx response to
> that INVITE. That same exact answer MAY also be placed in any provisional
> responses sent prior to the answer. The UAC MUST treat the first session
> description it receives as the answer, and MUST ignore any session
> descriptions in subsequent responses to the initial INVITE.
>
> But I am not sure what happens if the 2xx is not the same as the 183 in
> your case. We have interworked with an Ericsson
> switch which will fail the call if an unexpected SDP or SDP version change
> is received.
>
>
>
> ?
> Stephen James
> sjames_1958 at yahoo.com
> ?
> We are not princes of the earth, we are the descendants of worms, and any
> nobility must be earned.
>
>
>
> ________________________________
> From: Pranav Damele <pranavdamele at gmail.com>
> To: ankur bansal <abh.ankur at gmail.com>
> Cc: "discussion at sipforum.org" <discussion at sipforum.org>
> Sent: Saturday, June 15, 2013 8:26 AM
> Subject: Re: [SIPForum-discussion] P-Early-Media and Offer-Answer Relation
>
>
>
> Hello Ankur,
>
> I believe you should use UPDATE method when an early-media has been
> established and you need to modify the characteristics of that?session
> rather than 200 OK.
>
>
> Regards,
>
> Pranav Damele
> ARICENT
> Senior Engineer - Testing
>
> Mobile:?+91-9818-92-4466
> Email:?pranavdamele at gmail.com
> IM:?pranavdamele?(Skype)
> ?http://in.linkedin.com/in/pranavdamele
>
>
> On 14 June 2013 16:04, ankur bansal <abh.ankur at gmail.com> wrote:
>
> Hi All ,
> >
> >
> >I have come across one sceanrio :
> >?
> >Invite sdp(O1)---------------------->
> >183 sdp V1(A1) <----------------------
> >200 sdp V2 <-----------------------------
> >ACK ------------------------------------->
> >
> >
> >Here Sdp coming in 183 and 200 is same but server sending diff versions
> for both.
> >As offer answer is complete after 183 sdp ,how should we handle ?200 sdp ?
> >? 1. Assuming 200 sdp as new offer and send answer in ACK ?
> >? 2. Ignore 200 sdp as offer answer already completed ?
> >
> >
> >Also note 183 is coming with P-Early-Media header .
> >Does P-Early-Media in 183 response gives us any flexibility regarding
> Offer answer model or not ?
> >?
> >
> >
> >
> >Thanks & regardsAnkur Bansal
> >_______________________________________________
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> >
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