IP TELEPHONY: From Evolution to Revolution… from Emerging to the Inevitable

The world of telephony has changed a lot since Alexander Graham Bell’s first call more than a century ago. The major breakthroughs have been the introduction of automatic exchanges, digitization of those exchanges, implementation of digital telephony, use of satellites and fiber optics for communications and the coming of mobile telephony. These have all been improvements over the basic theme of an end-to-end circuit switched connectivity.

However, the coming of the Internet and the subsequent development of Internet Protocol Telephony, IP Telephony in short, changed all that. IP telephony encompasses many different ways of transmitting voice, fax and related services over packet-switched IP-based networks. It is also used as a generic term to cover voice over Frame Relay and voice over xDSL. For the record, IP telephony can be divided into two major sub-groups – Internet Telephony and Voice over IP. While the former uses the public Internet network for voice traffic and is highly disorganized, with little QoS guarantee; the latter refers to voice traffic over a managed IP-based network. There are QoS issues involved in VoIP also, but they are being worked out, allowing a number of carriers worldwide to offer integrated voice and data services.

The Evolution of IP Telephony

IP means a lot … to the core network operators	… and to the local service providers	…and the corporate enterprises
One network for voice, data and video Scalable and flexible service architecture Bits are bits are bits: simplified manageability Allows focus on speed, the differentiator, without worrying about what goes in to the network	Lower entry costs Low risk market access No dependence on proprietary technology Fast network roll out Shorter time to market One network for voice, data and video New service opportunities Rich value-added services menu Unified messaging Multimedia support Multiple billing options Enhanced service customization ability A lot of flexibility and speed	Does much more than just reduce voice call costs Voice and data convergence on one network No need of PBXs, which are closed architecture products Scalable and flexible architecture Huge savings on moves, adds and changes Ease of management Low ongoing maintenance and management costs Easy prioritization of bandwidth usage VoIP supports new levels of personal mobility

While Internet telephony has usually meant low cost or even free voice calls, VoIP has been much more than this for the core network operators, local exchanges and corporate enterprise.

Ravi Shekhar Pandey