Howto:SIP Reverse Negotiation - Call Transfer: Difference between revisions
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#ACK with SDP-Answer | #ACK with SDP-Answer | ||
(RFC | References: | ||
* RFC 3261 "SIP: Session Initiation Protocol" (June 2002) | |||
* RFC 3725 "SIP 3pcc" (April 2004) | |||
* RFC 6337 "SIP Usage of the Offer/Answer Model" (August 2011) | |||
<font color="red"><b>For the Interop with innovaphone the support of the Reverse-Negotiation | <font color="red"><b>For the Interop with innovaphone the support of the Reverse-Negotiation is very important!</b></font> | ||
*The Reverse-Negotiation is needed for Call-Transfer. | *The Reverse-Negotiation is needed for Call-Transfer. | ||
*The Reverse-Negotiation is needed for Call-Pickup. | *The Reverse-Negotiation is needed for Call-Pickup. | ||
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[[Howto:Does the innovaphone IP200 support RFC 3261 aka SIP?]] | [[Howto:Does the innovaphone IP200 support RFC 3261 aka SIP?]] | ||
[[Howto:SIP Media Negotiation - Details]] | |||
[[Category:Howto|{{PAGENAME}}]] | [[Category:Howto|{{PAGENAME}}]] |
Latest revision as of 13:34, 21 November 2014
Applies To
This information applies to
- all innovaphone products
The need of Reverse-Negotiation.
Reverse-Negotiation means:
- INVITE without SDP
- 200/OK with SDP-Offer
- ACK with SDP-Answer
References:
- RFC 3261 "SIP: Session Initiation Protocol" (June 2002)
- RFC 3725 "SIP 3pcc" (April 2004)
- RFC 6337 "SIP Usage of the Offer/Answer Model" (August 2011)
For the Interop with innovaphone the support of the Reverse-Negotiation is very important!
- The Reverse-Negotiation is needed for Call-Transfer.
- The Reverse-Negotiation is needed for Call-Pickup.
- The Reverse-Negotiation is needed for Call-Forking (Broadcast Group and Multiple Registrations).
Example Call-Transfer with consultation (Attended Transfer):
- A is connenced with B through PBX.
- B is connenced with C through PBX.
- B initiates a Transfer (sends REFER with Replaces to PBX).
- A and C have to be connected by the PBX.
- Therefore A and C need to do a Media-Negotiation.
- Therefore one of the subsribers must provide an SDP-Offer, that is passed through to the other.
- Therefore the PBX starts an Reverse-Negotiation to one of the both partners, for instance A ..
- A gets an INVITE without SDP.
- A answers with 200/OK with SDP-Offer.
- This SDP-Offer will be forwarded by the PBX with an INVITE to C.
- C selects the coder and answers with 200/OK with SDP-Answer.
- This SDP-Answer will be forwarded with an ACK to A.
- C gets from the PBX an ACK without SDP.
Related Articles
Howto:Supported SIP Features and List of RFC's