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Introduction to Internet telephony

This is the first tip in a series excerpted from a report by Ohio State University. The report analyzes issues and challenges in the evolving VoIP technology.

"Migrate to IP or risk being left behind." This seems to be the idea in the minds of vendors who have been using circuit switching infrastructures for the transportation of voice. As you are reading this article, the Internet is being modified to support voice traffic and products are being made to link the data and voice networks. Eventually the Internet and the telephone network will be one and the same.

Internet telephony is an emerging technology and has a number of technological and evolutionary issues. The technological issues are mainly because the Internet was not designed for real time traffic such as voice and video. The evolutionary issues stem from the fact that a variety of vendors develop their products according to market demands and supplies. It will take time for all these products to converge and work with the same reliability as the circuit switched networks. However the benefits of using IP as a generic platform for both data and real time applications are compelling enough to encourage resolution of these issues.

The following sections describe the benefits of this technology, the issues related to the technology, the challenges ahead and also present a survey of the current VoIP products in the market, the services provided and how well they handle the issues.

Benefits of the technology

Integration of voice and data
The integration of voice and data traffic will be demanded by multi-application software. The inevitable evolution will be Web servers capable of interacting with voice, data and images.

An integrated infrastructure that supports all forms of communication allows more standardization and lesser equipment management. The result is a fault tolerant design.

Network efficiency
The integration of voice and data effectively fills up the data communication channels efficiently, thus providing bandwidth consolidation. The idea is to move away from the TDM scheme wherein the user is given bandwidth when he is not talking. Data networks do not do this. It is a big saving when one considers the statistics that 50% of a conversation is silence. The network efficiency can be further boosted by removing the redundancy in certain speech patterns.

Cost reduction
The Public Switched Telephone Networks' toll services can be bypassed using the Internet backbone, which means a slash in prices of the long distance calls. However these reductions may slightly decrease when the Federal communications Commission (FCC) removes the Enhanced Service Provider (ESP) status granted to Internet service providers (ISPs) by which they do not have to pay the local access fees to use the telephone company (TELCO) local access facilities. Access fees form a significant part of all long distance calls. But in spite of this, the circuit switched telephony would be expensive because of lack of bandwidth consolidation and speech compression techniques.

New applications

Directory services over telephones
Ordinary telephones can be enhanced to act as an Internet access device. Directory services could be implemented by submitting a name and receiving a reply.

Interoffice trunking over the corporate intranet
The tie trunks between company owned PBXs could be replaced by an Intranet link and would provide large savings at a good quality of service.

Remote access to the office from your home
One's home could be converted to a home office and gain access to the company's voice, data and fax services using the company's Intranet.

IP-based call centers
With the advent of the Internet, companies have experienced large increase in their Web site inquiries. These may not result in immediate financial transaction, but at least people get to know about their products. This is the beginning of e-commerce. With VoIP there can be interaction with the customers.

Fax over IP
Real time facsimile transmission is an immediate application of Voice over IP. Facsimile services which use dial-up PSTN services are affected by high cost for long distance, analog signal quality and machine compatibility. Instead a fax interface unit can convert the data to packet form, handle the conversion of signaling and controlling protocols and ensure complete delivery of the data in correct order.

This tip is reprinted with permission from the report "Voice over IP: Products, Services and Issues" by Vinodkrishnan Kulathumani at Ohio State University.

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