Subject: [Insipid] 3.X 3PCC Use Case: evaluation

From: James Polk <[email-masked]>
Date: Mon, 27 Aug 2012 18:26:54 -0500

INSIPID

Here is the set of use-cases and requirements discussed in Vancouver. 
We are to come to consensus on each of these (or not), and if we 
agree the use-case or requirement should be in the document, we need 
to determine acceptable wording for each. The Subject: line will 
contain the specific topic (which use-case or requirement) for this 
thread. PLEASE do not cross contaminate the threads. Any new topic 
SHOULD have its own Subject line. The chairs will monitor and call 
for consensus on each use-case and requirement (and wording of each).

Please make constructive suggestions regarding each you care about.

The Section numbers will be reordered once consensus has been reached 
on all items we're covering, so don't worry about that part.

3.X 3PCC Use Case:

Third party call control refers to the ability of an entity to create 
a call in which communication is actually between two or more 
parties. For example, a B2BUA acting as a third party controller 
could establish a call between two SIP UA's using 3PCC procedures as 
described in section 4.1 of RFC 3725 the flow for which is reproduced below.

               A              Controller               B

               |(1) INVITE no SDP  |                   |

               |<------------------|                   |

               |(2) 200 offer1     |                   |

               |------------------>|                   |

               |                   |(3) INVITE offer1  |

               |                   |------------------>|

               |                   |(4) 200 OK answer1 |

               |                   |<------------------|

               |                   |(5) ACK            |

               |                   |------------------>|

               |(6) ACK answer1    |                   |

               |<------------------|                   |

               |(7) RTP            |                   |

               |.......................................|

                Figure 1. Session-ID 3PCC Scenario

Such a flow must result in a single session identifier being used for 
the communication session between UA A and UA B.

Derived Requirements: REQ10

---

From: Brett Tate <[email-masked]>
Date: Tue, 28 Aug 2012 06:48:05 -0700

> 3.X 3PCC Use Case:
> 
> Third party call control refers to the ability of an entity 
> to create a call in which communication is actually between 
> two or more parties. For example, a B2BUA acting as a third 
> party controller could establish a call between two SIP UA's 
> using 3PCC procedures as described in section 4.1 of RFC 3725 
> the flow for which is reproduced below.

<snip>

> 
> Such a flow must result in a single session identifier being 
> used for the communication session between UA A and UA B.
> 

As far as I know, this use case should not be added since it does not meet the "one in / one out case where the To/From header fields could have been preserved" situation.  Thus I think that the use case should not be included within draft.

If such 3PCC specific use cases are actually within scope for insipid, the use case should clarify if the "single session identifier" is allowed to change after the dialog is established.

Thanks,
Brett