VoIP: KNOWLEDGE POWER – Internet Telephony

We have been hearing so much about the Internet telephony during the last few years. Initially, the Government was dithering over the decision to allow Internet telephony in the country mainly due to pressure from various groups but as we know, technology is unstoppable. Internet telephony has finally become a reality since the Government has allowed it from April 2002. Various ISPs are at different stages of implementing this service.

What is Internet telephony/VoIP?

Internet telephony refers to communications services—voice, facsimile, and/or voice-messaging applications that are transported via the Internet, rather than the public switched telephone network (PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.

How has Internet telephony evolved over the years?

The possibility of voice communications traveling over the Internet, rather than the PSTN, first became a reality in February 1995 when Vocaltec, Inc. introduced its Internet Phone software. Designed to run on a personal computer (PC) equipped with a sound card, speakers, microphone, and modem, the software compressed the voice signal and translated it into IP packets for transmission over the Internet.

In a relatively short period of time since then, Internet telephony has advanced rapidly. Many software developers now offer PC telephony software but, more importantly, gateway servers are emerging to act as an interface between the Internet and the PSTN. Equipped with voice-processing cards, these gateway servers enable users to communicate via standard telephones.

A call goes over the local PSTN network to the nearest gateway server, which digitizes the analog voice signal, compresses it into IP packets, and moves it onto the Internet for transport to a gateway at the receiving end. With its support for computer-to-telephone calls, telephone-to-computer calls and telephone-to-telephone calls, Internet telephony represents a significant step toward the integration of voice and data networks.

What are the advantages of VoIP?

A major advantage of VoIP/ Internet telephony is that it avoids the tolls charged by ordinary telephone service. Originally regarded as a novelty, Internet telephony is attracting more and more users because it offers tremendous cost savings relative to the PSTN. Users can bypass long-distance carriers and their per-minute usage rates and run their voice traffic over the Internet for a flat monthly Internet-access fee.

What are the different types of VoIP Applications?

A wide variety of applications are enabled by the transmission of VoIP networks. For example an organization with many branch offices wants to reduce costs and combine traffic to provide voice and data access to the main office. This is accomplished by using a packet network to provide standard data transmission while at the same time enhancing it to carry voice traffic along with the data.

Another application of VoIP software is interworking with cellular networks. The voice data in a digital cellular network is already compressed and packetized for transmission over the air by the cellular phone. Packet networks can then transmit the compressed cellular voice packet, saving a tremendous amount of bandwidth.

What are the current problems in Internet telephony?

The current reliability and sound-quality problems of Internet telephony are attributable to limitations in Internet bandwidth and compression technology.

The public Internet will be able to transport voice calls reliably and with high quality when various technologies deliver greater backbone-network and subscriber-access speeds

Which is the market segment that is likely to be the major driver of Internet telephony growth?

In the near term, the market segment expected to be the biggest driver for VoIP telephony is corporate intranets/extranets.

Which factors shall guide the future of Voice-over-Internet Protocol (VoIP) Telephony?

Several factors will influence future developments in VoIP products and services. Currently, the most promising areas for VoIP are corporate intranets and commercial extranets. Their IP–based infrastructures enable operators to control who can and cannot use the network.

Another influential element in the ongoing Internet-telephony evolution is the VoIP gateway. As these gateways evolve from PC–based platforms to robust embedded systems, each will be able to handle hundreds of simultaneous calls. Consequently, corporations will deploy large numbers of them in an effort to reduce the expenses associated with high-volume voice, fax, and videoconferencing traffic. The economics of placing all traffic— data, voice, and video over an IP–based network will pull companies in this direction, simply because IP will act as a unifying agent, regardless of the underlying architecture (i.e., leased lines, frame relay, or ATM) of an organization’s network.

Commercial extranets, based on conservatively engineered IP networks, will deliver VoIP and facsimile over Internet protocol (FAXoIP) services to the general public. By guaranteeing specific parameters, such as packet delay, packet jitter, and service interoperability, these extranets will ensure reliable network support for such applications.

VoIP products and services transported via the public Internet will be niche markets that can tolerate the varying performance levels of that transport medium.

Telecommunications carriers most likely will rely on the public Internet to provide telephone service between/among geographic locations that today are high-tariff areas. It is unlikely that the public Internet’s performance characteristics will improve sufficiently within the next two years to stimulate significant growth in VoIP for that medium.
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