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Host Notification of Selective SIP Header Information

Overview

With this feature, the CSP can send selective SIP header data to the host application in the Request For Service with Data message and, if required, in the PPL Event Indication message. The Call-ID header information allows the host application to uniquely identify the call with other elements in the SIP network.

Important! You should disable all additional SIP header notification if calls are being internally routed without host application intervention.

Description

The process works as follows:

1. The host application specifies what additional fields from the SIP message header that it wants to see in the Request For Service with Data message.

2. You specify the fields in the 0x027F SIP Message Information Mask in the VoIP Protocol Configure message.

3. If the CSP can fit all of the data in the Request For Service with Data message, it does so. (The data is formatted in the NPDI TLVs listed below these steps.)

4. If the size exceeds the maximum size that the CSP allows (320 bytes of NPDI data), the CSP sends the following:

• the Request For Service with Data message with NPDI data (not to exceed 320 bytes) including the Subsequent Info Status 0x2953 TLV indicating that there is more data to follow.

• The CSP sends "n number" of PPL Event Indications messages where each indication would carry NPDI data (not to exceed 320 bytes) including the Subsequent Info Status 0x2953 TLV

5. If the CSP sends the data in multiple messages (Request for Service and subsequent PPL Event Indication) the CSP adds the Subsequent Info Status 0x2953 TLV. This TLV indicates the sequence number of the message and whether it is the last message in the sequence.

6. If the data has to go into an API message, and not into TLVs, the call is rejected with the "500 Internal Server Error" response.

API Messages Used

• Request For Service with Data (0x002D)

• PPL Event Indications (0x0043)

Session-Initiation Protocol. A signaling protocol used for establishing sessions in an IP network. A session could be a simple, two-way telephone call, or it could be a collaborative multi-media conference session.
RFS. A Status Message indicating that some entity is requesting service from the Excel platform.
See Programmable Protocol Language.
Voice over Internet Protocol. The delivery of voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public-switched telephone network (PSTN).
Network Protocol Data Intelligence. Also called “Interworking,” it is a software product that operates within Excel’s Call Control (Layer 4) and Services (Layer 5) call processing layers. NPDI is meant to enhance Excel’s call processing product offering by allowing call processing layers (specifically Layers 4 and 5) to perform advanced analysis, generation, and conversion of Network Signaling (NS) Layer 3 information.
Tag-Length-Value block. A standardized block that allows data to inserted in a standard way into API messages.
A condition that, when met, drives a state machine from one state to another. A condition that drives a Component out of its current state by invoking an associated primitive.