Call Flow Messages

The generic format of the API messages below are documented in the API Reference. The following is specific to SIP Call Control.

The following are three example of how to use the Route Control message with SIP software. This Route Control message assumes that you are using a local Registration on the CSP. The outbound INVITE Request message is directed using Registration information matching the specified To User Name.

This Route Control message creates an outbound INVITE Request message directed using the specified user@host name. (The user is not locally registered.)

This Route Control message creates an outbound INVITE directed to the default Proxy IP address and uses the specified "To" User Name.

The CSP reports incoming calls from the SIP side using the Request for Service with Data (0x002D) message. An Extended Data ICB NPDI Universal Data (0x33) is used in SIP. The UPDF parameters supported are the same as those supported in the Route Control message.

You can use the following TLV to encode the SIP response code to be used in the SIP response message generated by the CSP.

To release an incoming SIP call with 404 reason

H->X
00 20 00 36 00 00 ff 00 02 0d 03 00 01 08 0d 03 00 01 08 33 01 03 00 33 00 08 00 01 29 15 00 02 01 94

Used to encode the SIP response code when an outbound SIP call is rejected by the remote SIP UA.

OUTBOUND call rejected by remote side with 404 reason

X -> H
00 1a 00 69 00 04 ff 00 01 0d 03 00 01 0b 01 03 00 33 00 08 00 01 29 15 00 02 01 94

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.

Setting up, monitoring, and tearing down calls.

See Address Information Block.

Internet Protocol. Part of the TCP/IP family of protocols used to route messages and tracks the addresses of nodes.

See Information Control Block.

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.

See Universal Protocol Data Format.

Tag-Length-Value block. A standardized block that allows data to inserted in a standard way into API messages.