The Deployment of Features in Internet Telephony

By Dongyang Zhang, B.Eng

A thesis submitted to the Faculty of Graduate Studies and Research
in partial fulfilment of the requirements for the degree of Master of
Applied Science in Electrical Engineering

Ottawa-Carleton Institute for Electrical and Computer Engineering
Faculty of Engineering
Department of Systems and Computer Engineering

Carleton University
Ottawa, Canada, K1S 5B6
January 10, 2002


Abstract

Internet telephony enhances existing telephone features and creates a
number of new features with the integration of Internet services. Basic
features can be divided into client features and network features
according to their characteristics. Distributed Feature Composition (DFC)
is a new architecture to describe telecommunication features. Session
Initiation Protocol (SIP) and the Call Processing Language (CPL)
presented by the Internet Engineering Task Force (IETF) can be regarded
as a service architecture of Internet Telephony. This thesis discusses the
deployment of features based on the SIP protocol and the DFC architecture
respectively, which is mainly concerned with pure signalling messages. In
the SIP protocol, it is more desirable to deploy most client features
in end devices if end users are online. In the DFC architecture, it
is better to place most client features inside the network. However,
network features must be provided inside the network. The modularized
DFC architecture introduces signalling overhead although it brings many
advantages. Based on the DFC architecture, this thesis also sketches
out the design of a voice mail feature.  In addition, aside from pure
signalling messages, other issues regarding the deployment of features
will be presented.