[SIPForum-discussion] Is (200)Ok without Ringing (180, 183) a right approach?

[Rob Maxwell]

In  other protocols, (ISUP / ISDN), this call flow is called "fast answer".

It is allowed as long as the answer, 200 OK, has SDP.




From: Corey Thornburg 
Sent: Thursday, September 16, 2010 11:53 AM
To: Sachin Parnami ; discussion at sipforum.org 
Subject: Re: [SIPForum-discussion] Is (200)Ok without Ringing (180, 183) a right approach?


It is acceptable, yes.  However, in general I have usually seen a 180 even if the call is auto answered.

 

 

Rosenberg, et. al.          Standards Track                    [Page 83]

 

RFC 3261            SIP: Session Initiation Protocol           June 2002

 

 

   contains a session id and version number in the origin (o) field.  If

   the user is already a member of the session, and the session

   parameters contained in the session description have not changed, the

   UAS MAY silently accept the INVITE (that is, send a 2xx response

   without prompting the user).

 

   If the INVITE does not contain a session description, the UAS is

   being asked to participate in a session, and the UAC has asked that

   the UAS provide the offer of the session.  It MUST provide the offer

   in its first non-failure reliable message back to the UAC.  In this

   specification, that is a 2xx response to the INVITE.

 

   The UAS can indicate progress, accept, redirect, or reject the

   invitation.  In all of these cases, it formulates a response using

   the procedures described in Section 8.2.6.

 

 

Corey Thornburg 

VoIP Architect

 

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Sachin Parnami
Sent: Wednesday, September 15, 2010 11:38 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Is (200)Ok without Ringing (180, 183) a right approach?

 

Hi *,

Is it a right approach to send Ok (200) without Ringing(180) or Session in Progress (183)? as these are provisional responses.

UE1                                             UE2
 |              INVITE                            |
 |-------------------------------------------------->|
 |              TRYING (100)                  |
 |<------------------------------------------------- |
 |                     OK (200)                  |
 |<--------------------------------------------------|

Does it abides standards of RFC 3261?

-- 
Regards,
Sachin Parnami



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