The Phone meets the Web - An Overview of Internet Protocol Telephony

Tuesday 23 May 2006

Keith Dyer, Systems Engineer, Cisco Systems Ltd


Keith Dyer, who will be known to some of you as a former Committee member, opened his talk with a short introduction to Cisco Systems and his role as a Systems Engineer specialising in the needs of small and medium businesses. He then outlined the current state of the market and the motivations for businesses to adopt IP Telephony.

A simple definition of IPT is the routing of voice telephone calls over any IP-based network such as the Internet or a corporate local- or wide-area network. This is also referred to as Voice over IP or VoIP. The terms Internet Telephony and Broadband Telephony may also be encountered; they all refer to the same thing.

Traditionally, separate network infrastructures have been deployed for voice and data traffic, such as public switched telephone networks (PSTN) for voice and LANs / WANs for data. This imposes the overhead of having to maintain two network infrastructures. Additionally, traditional circuit-switched networks are not suitable for handling simultaneous voice and data traffic - particularly when the two are synchronised - because they were not designed for this.

The benefits of IPT

As contracts that organisations have with telecommunications providers come up for renewal, some organisations are now viewing this as an opportunity to rationalise their infrastructures (and possibly the number of suppliers they deal with) by considering the use of IP Telephony for their voice traffic.

Some vendors are proposing to phase out support for PBX (private branch exchange) equipment in the near future and this is another reason for organisations to consider making the change. Also, IPT implementations can make use of open standards for interfaces, which means that organisations are less likely to be restricted to a single supplier.

The “hybrid” model

Organisations that are currently implementing IPT may be using ‘hybrid’ infrastructures, where the PBX interfaces with IP routers to direct voice traffic over the LAN or WAN. This means that the PSTN is retained as a backup, and allows existing telephone equipment to be used with an IPT solution.

IP phones, which can be connected directly to an IP network, are now available and these can be used to build a pure IPT system. These can include display screens allowing video or documents to be displayed on screen along with the voice signal being delivered.

Keith then described some solutions offered by Cisco as examples of applications that provide benefits from IPT. These include unification of voice mail with email, allowing voice messages to be retrieved through email clients and integrated audio/video conferencing allowing sharing of documents and other data as part of a conference call, all using the same device (such as an IP phone).


Thanks must go to Keith for an informative and well-presented talk, which showed no sign of the fact that he had stepped in at short notice to give the presentation after the original speaker had to pull out.