McDewey

Error scenarios that may result in announcements during call setup include vacant code and certain call setup failures that result from MLPP. INFO Packages During the life of an INVITE dialog, INFO packages allow SIP UAs to exchange negotiated content without managing and correlating a subscription. The INFO package negotiation occurs during initial call setup and is remembered throughout the life of the INVITE dialog. This is independent of the number of times the endpoint is subject to some feature interaction such as transfer or conference. Unified Communication Manager supports the conference package. The negotiation works according to the rules spelled out in the following draft: draft-ietf-sip-info-events-01.txt. INFO Conference Package Negotiation Unified Communication Manager is a B2BUA. As such, each endpoint has their own specific INVITE dialog with Unified Communication Manager, when a call is established. Due to feature invocations, Unified Communication Manager can move the media around, while maintaining the original INVITE dialog. For example, if A transfers B to C, B and C get reINVITEs and UPDATEs to redirect their media towards each other and to update the connected party information. The original dialogs established between B and Unified Communication Manager and C and Unified Communication Manager prior to the transfer remain intact. The conference INFO package negotiation occurs during initial call setup and is remembered throughout the life of the INVITE dialog. This is independent of the number of times the endpoint is subject to some feature interaction such as transfer or conference. The actual conference package XML is borrowed from the following RFC: • RFC-4575: A Session Initiation Protocol (SIP) Event Package for Conference State. RFC defines the package in the context of the SUBSCRIBE/NOTIFY framework. The same XML schema can be used in the INFO event package framework. The negotiation within the context of Unified Communication Manager works the following way: When A calls B, this is two distinct dialogs since Unified Communication Manager is a B2BUA. In this example, A is the initiator of the dialog between A and Unified Communication Manager. On the other hand, Unified Communication Manager is the initiator of the dialog between Unified Communication Manager and B. The negotiation works based on who initiates the dialog and who is the sender versus receiver of the data. In our example, A and B are receivers and Unified Communication Manager is the sender of conference roster updates. Figure 2: Negotiation of Conference INFO Package, on page 34 shows how Send-Info and Recv-Info headers are used in this example to negotiate usage of INFO conference package. If an endpoint doesn’t include the header, Recv-Info: conference, then Unified Communication Manager will not send INFO messages with the conference package if the call is later connected to a conference. SIP Line Messaging Guide (Standard Edition) for Cisco Unified Communications Manager 33 SIP Standard Line Interface INFO Packages