Internet Telephony

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Internet Telephony
Project Implementation
The GUI of the implentation will be based on
'buddy list' style of many chat clients.
More providers are moving towards voice over IP
over traditional telephone networks. By combining
voice and data over the same network, clients are
cutting costs and gaining flexibility.
Throughout the project investigation a tool will
be created to customise VOIP services. The tool
will allow individual users or administrators to
build up blocks of call rules suited to a user or
companies needs, which may not specifically be
supported by vendors.

Like ordinary telephony, Internet telephony can
provide services such as call blocking and call
forwarding. However Internet telephony offers a
more flexible range of choices to heavily
personalise call control that have been enabled
by the Internet.
Project Investigation
Recently, several protocols have been created to
allow telephone calls over IP networks, notably
SIP 1 and H.323 2. These emerging standards
have opened up the possibility of a broad and
dramatic decentralization of the provisioning of
telephone services so they can be under the
user's control. IETF IPTEL work group has
proposed an architecture in which network devices
respond to call signalling events by triggering
user-created programs written in a simple,
static, non-expressively-complete language. This
language is called Call Processing Language. The
project will investigate the different ways to
implement VOIP services on a SIP server, in
particular by using the CPL language to customise
services.
Project Motivation
Call services are getting more popular these days
as new call processing technologies like VOIP are
introduced to the market and Internet is being
accepted by masses. It is becoming difficult for
the equipment vendors to support all possible
call services, as the number of possible
combinations of the call services is very high.
Vendors typically support basic call services
such as call blocking/forwarding etc, however
there is a need for clients to customize they're
own services for personal use.
Current Progress
Research in SIP and CPL has taken place. The SIP
server (a Sip Express Router server) is up and
running and is currently being set up to accept
CPL uploads to allow it to process calls. The
server authenticates users through a mySQL
database. Code from an open source project called
CPLEditor, is being used in the implementation to
upload CPL to the SIP server.