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Efficient REFER Mechanism for SIP Interactions

This draft proposes a REFER mechanism in SIP to avoid dialog creation and automatic subscription. It introduces the norefersub option tag and outlines preventing forking using GRUU. The feature allows REFER usage without implicit subscriptions.

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Efficient REFER Mechanism for SIP Interactions

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  1. REFER with no Implicit Subscription draft-ietf-sip-refer-with-norefersub-01 By Orit Levin oritl@microsoft.com SIP WG IETF62

  2. REFER with no Implicit Subscriptiondraft-ietf-sip-refer-with-norefersub-01 • Motivation • Allow for REFER without creating a dialog and automatic subscription to the Dialog event package • Mechanism • New option tag norefersub is defined and registered with IANA • Forking MUST be prevented (for example, using GRUU) • Status • “Last Called” a month ago • All the comments were incorporated except for the new thread from the last week SIP WG IETF62

  3. How does REFER-Issuerenables the feature? • Commonly is preceded by OPTIONS (or other previous engagement between the UAs) • Supported Header in the Request • REFER-Issuer is willing supporting the feature for the particular REFER • Required Header in the Response • If the REFER-Recipient chooses to not establish the subscription, it includes the tag in the Require Header in the response • Require Header in the Request • Is used by REFER-Issuer when it mandates using the feature for the particular REFER SIP WG IETF62

  4. REFER-Issuer suggests using the feature to REFER-Recipient REFER- Issuer REFER- Recipient REFER- Issuer REFER- Recipient REFER (Supported) REFER (CreateSUB = NO) 200 OK (Required) 2xx Current Draft Jonathan SIP WG IETF62

  5. Should we allow for Require Header usage with “norefersub”? REFER- Issuer REFER- Recipient REFER- Issuer REFER- Recipient REFER (Required) REFER (Supported) 420 Bad Extension 2xx REFER NOTIFY 481 (Call/Transaction Does Not Exist 200 OK Current Draft Cullen SIP WG IETF62

  6. The Resolution… SIP WG IETF62

  7. REFER with no Implicit Subscription Example REFER sip:carol@chicago.example.com SIP/2.0 Via: SIP/2.0/UDP client.atlanta.example.com;branch=z9hG4bKg45 Max-Forwards: 70 To: Carol <sip:carol@chicago.example.com> From: Alice <sip:alice@atlanta.example.com>;tag=5534562 Call-ID: 849392fklgl43 CSeq: 476 REFER Contact: <sip:uf313a413@example.com> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Accept: application/sdp Refer-To: <sip:3402934234@example.com> Supported: norefsub, gruu, … Require: norefersub Content-Length: 0 SIP WG IETF62

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