Support REFER Request in Call Agent

Purpose

This feature allows the CSP to process an inbound REFER request and to generate an outbound REFER request in Call Agent Mode.

This section contains the following:

• Description of the feature

• Sample calls flows

• API and PPL changes to support the feature

Description

Whenever there is an incoming REFER request, the REFER-TO header is reported to the host in the PPL Event Indication (Event 0x0021; Component 0x00A7). The host can propagate the REFER request to the outbound leg using the PPL Event Request message (Event 0x0027; Component 0x00A7).

The status of the reference is reported to the SIP component in the NOTIFY messages. This status is reported to the host in the PPL Event Indication (Event 0x0028; Component 0x00A7).

Call Flows

The following call flows show three scenarios:

• Success REFER request and NOTIFY message in Call Agent Mode (Includes sample API and SIP message traces.)

• REFER Request Failure in Call Agent Mode

• Reference Failure in Call Agent Mode

Successful REFER and NOTIFY in Call Agent Mode

This call flow assumes that the Referrer and Referee are in the answered state. The second PPL Event Request (0x0020) to generate the NOTIFY message is not supported as of now, but will be supported in a future release.