Authentication

Excel has implemented SIP Authentication which includes protective measures to prevent an active attacker from modifying and replaying SIP requests and responses.

SIP authentication enables the Excel platform to validate legitimacy of the subscribers. It is like any login/password based scheme. It ensures that only valid users can make calls through the Excel platform.

The same cryptographic measures that are used to ensure the authenticity of the SIP message also serve to authenticate the originator of the message. SIP extends the HTTP WWW Authenticate and Authorization header field and their Proxy- counterparts to include cryptographically strong signatures.

The enhancements include support for both authentication and authorization using digest and basic.

The host uses the PPL Event Request message with event ID (12, 0x0C) to authenticate incoming SIP calls.

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.

Hypertext Transfer Protocol. The protocol used by web servers and client browsers to communication.

See Programmable Protocol Language.

In PPL, a condition that, when met, drives a state machine (PPL Component) from one state to another, by invoking an associated Primitive. In PPL files, an Event is marked by an arrow and text.

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.