Two cans and a string - 1998 style

Communications News, Feb, 1998 by Morris Edwards

Internet telephony is maturing quickly, spurred not only by the prospect of cheaper phone bills, but also by the opportunity of integrating voice with a variety of Webbased data services.

For phone calls to travel over the Internet, the voice signals must first be converted to compressed, packetized data suitable for transporting via TCP/IP (transmission control protocol/internet protocol). The reverse process takes place at the receiving end to complete the phone call. With the right equipment and software, users can call anywhere and talk forever without paying long-distance charges.

Despite these cost savings, though, the greatest potential for voice over IP may lie with applications that merge voice and data traffic -- and ultimately video as well. In a call center application, for instance, Internet telephony allows a customer browsing a firm's Web site to talk to a sales or service agent simply by clicking on an icon.

Recognizing this opportunity, Cisco Systems, Lucent Technologies, and other major vendors have recently announced products to support voice, fax and multimedia applications on the Internet or over corporate intranets and private networks using the Internet Protocol (IP).

They join a growing roster of smaller companies -- such as Voxware, VocalTec, and NetSpeak -- who pioneered Internet telephony and continue to set the pace in technology development.

Voxware is the leader in the compression/decompression (codec) technology needed to prepare the digitized voice packets for transport over the Internet and to reconstruct the voice signals at the receiving end.

Routing the packets through the Internet can create significant delays, depending on the paths taken and the amount of congestion at the routing nodes. When packets are late or lost, the codec compensates by averaging over the gaps, impairing voice quality.

With its most recent offering, the VIPSuite software development kit, the Princeton, N.J., firm claims to have greatly improved the quality of two-way voice conversations over IP networks such as the Internet.

Voxware's codec is frequency-based rather than time-domain-based, allowing it to extract more information from the speech stream and to reconstruct it more accurately for late or lost packets. Also, it sets up a feedback link so the receiver can tell the transmitter how best to packetize and ship the data based on measured packet delay and other network performance parameters.

VocalTec dominated early development with its InternetPhone, which was aimed primarily at computer hobbyists willing to accept poor voice quality and other inconveniences with the fledgling technology.

More recently, the Northvale, N.J., firm has targeted corporate users with a gateway server and teleconferencing software called Atrium. The servers bridge the Internet and the public telephone network, allowing point-to-point calling with the connection to the destination phone completed over a local loop.

Atrium works with the server, enabling phone users to participate as they would in a regular conference call. Participants with PCs can also view Windows-based documents as they talk into the microphone.

NetSpeak Corp., of Atlanta, Ga., has also introduced gateway servers to leverage its initial WebPhone client software. Its Network Component Architecture provides a blueprint for building interoperable multimedia networks using its IP telephone client and server products.

Among the new innovators is Aplio, Inc., of San Bruno, Calif., which recently introduced a stand-alone device for converting a regular phone into one able to make calls over the Internet.

With the Aplio/Phone, a caller dials a phone number in the normal manner and then pushes a button to converse over the Internet. The initial product limits calls to other Aplio/Phone users, but the next release will reportedly allow communications with any H.323-compatible device, including a PC with the appropriate Internet telephony software.

Larger vendors have typically focused on gateway servers for their foray into the Internet telephony or IP voice market.

Lucent Technologies' Internet Telephony Server (ITS) family is based on a Compaq ProLiant 2500 Pentium platform running Windows NT. The ITS server is compatible with the H.323 IP telephony standard. It lets users send and receive real-time voice and fax messages over the Internet or corporate intranet, with fallback to the public telephone network in case of service degradation.

Cisco Systems also has announced a voice packet gateway solution which it says will be the first in a series of products to support voice and fax over IP networks.

Available initially for the Cisco 3600 router, the gateway allows a company to offload branch-office voice traffic from the public telephone network, for instance, and route it across the corporate intranet, eliminating toll charges. Likewise, interoffice fax could be routed across the intranet or through an extranet.

Since the gateway interfaces with existing phones, fax machines, key systems and PBXs, it makes the process of placing calls over the IP network transparent to users. Cisco says it has developed a framework with its IOS software that supports the H.323 specification and provides for seamless integration of voice, data, and call control.