Software Overview

The SIP software provides User Agent Client (UAC), User Agent Server (UAS), and Location Server registration functionality. The implementation in this release has the following key attributes and features.

With a Matrix Controller implementation, SIP software is independent of hosts and line cards. This feature enables partners to upgrade to the next generation of SIP software and IP Network Interface cards independently.

UPDF allows for seamless protocol interworking, whether it entails various IP protocols (SIP endpoint to an H.323 endpoint) or IP-to-PSTN signaling.

The SIP software gets the RTP Payload Type and Payload size from the Route Table or Route Control message. If the type and size are not specified in either of those, the SIP software uses the IP Network Interface defaults.

The User Agent communicates with Layer 4 and the IP Network Interface card to perform SIP-controlled operations. The User Agent communicates with Layer 4 over a TCP/IP socket, and uses UDP or TCP to communicate externally with other SIP devices.

SIP software allows a Cantata partner application to work with the CSP to provide services in the IP Services Node. Existing partners with applications that provide circuit node services can support SIP with minimal application changes.

The CSP ignores session level attributes in the SDP. The CSP accepts SDP's with a session level attribute placed between the time descriptor attribute ('t=') and media information attribute ('m='). This is the only exception - otherwise the CSP follows the attribute order as in RFC 2327 section 6. SIP requests with SDP in incorrect order are responded with 400 Bad Request.

• Whenever the mode of IP Network Interface Series 3 card is changed from gateway to normal mode (or vice versa), SIP still has the old profile (containing codec information) in its database. This remains, unless the host initiates a media resynchronization using TLV 0x0284 or the host makes another call that would use a module in this card.

• If the host initiates a media resynchronization, the profile (containing codec information) for all the modules in the card are deleted from SIP's database. All other profiles (if there are other cards) are refreshed.

• If the host makes a call that uses a module in this particular card, then the profile (containing codec information) for all the modules in the card are deleted from SIP's database. The profile for the module that this call would use, is queried and stored.

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.

In SIP, an application program that sends SIP requests (See also Session Initiation Protocol). Clients may or may not interact directly with a person. Users agents and proxies contain clients (and servers).

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

See Universal Protocol Data Format.

ITU-T standard defines a set of call control, channel setup, and codec specifications for transmitting real-time voice and video over networks that do not offer guaranteed service or quality of service.

Public Switched Telephone Network

Real-Time Transport Protocol. Supports transport of real-time data like interactive voice and video over packet-switched networks.

Call processing layer of the CSP.

Transmission Control Protocol / Internet Protocol. A networking protocol that provides communication across interconnected networks.

A device that translates calls between an IP network and another network, typically the PSTN.

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