Voice-over-IP telephony lets employees reach out and touch cohorts without leaving their PCs

Voice-over-IP telephony lets employees reach out and touch cohorts without leaving their PCs

By Jason Byrne
GCN Staff

For more than 120 years, telephones have been exchanging voice information as modulated electrical signals over point-to-point connections.

An Internet call, in contrast, compresses the voice data and breaks it down into packets at the sending end. The nature of intranets and the Internet practically guarantees that some packets will arrive out of order or vanish altogether. At the receiving end, an Internet phone must recompile the jumbled mess into an audio signal that sounds like a natural voice again.

As anyone experienced in transmitting or receiving information via TCP/IP knows, the Internet and local intranets are prone to congestion and unreliable performance. IP predates streaming multimedia by decades. New technologies and increased bandwidth, however, are helping to overcome IP's limitations for streaming data in real time.

Computer telephony vendors are trying out ways to send voice over data networks. The one thing most data networks have in common is reliance on distinct packets, so the correct umbrella term is voice over packet. But whether the network is asynchronous transfer mode, IP or frame relay, the problems of voice transmission are the same.

Voice-over-IP applications work best in environments that have a reliable connection and a certain amount of dedicated bandwidth. A small field office has to tie into the agency's existing network infrastructure anyhow, so why not put its voice service on the same connection? Depending on the long-distance charges, the agency might save a lot of money by simply piggybacking voice communications over the IP connection.

Products such as the MultiVOIP MVP 200 from Multi-Tech Systems Inc. of Mounds View, Minn., from not only let users make calls over IP networks, but they also can connect an entire office through a private branch exchange. The only limit on the number of users is the amount of dedicated bandwidth.

A remote user or office could even dial in through a virtual private network and make voice calls over the IP connection.

There are potential problems with a VPN or Internet connection, of course. But because voice band-width requirements are only about 6 Kbps, even a bad connection can be overcome.

Hardware might not be the right choice for a mix of remote offices and users. Software is less expensive and resource-intensive for PC-to-PC or PC-to-telephone setups. What is lacking is a standard for interoperability between hardware and software approaches, and among vendors' products.
Many software voice-over-IP products use the same basic technology and are interoperable. The international H.323 specification for sending voice, data and streaming video across IP networks is in place, although it is not an actual standard.

H.323 recommends ways to set up a connection and send data across it. But the recommendations are only good for traffic over IP networks. Interoperability requires not just a standard but also ways to resolve quality-of-service problems such as compression, echo and transmission delay.
For the moment, it probably is advisable to choose one voice-over-IP vendor and stay with it. As standards evolve and the technology advances, upgrading an existing setup should not force a complete revamp of the network infrastructure.

In the end, all kinds of digital traffic will likely share the same pipe. Already a voice-over-IP box in Australia can make a free phone call to one in Maine by piggybacking on an existing data network. The cost savings alone will revolutionize how we use data and what we mean by a communications infrastructure.

As adoption spreads, network backbones will urgently need upgrades. But it comes down to making one investment that benefits two different data streams, and that makes sense.


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