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Second Quarter 1998

ISDN: The Future Of Internet Telephony


ISDN (Integrated Services Digital Network) is experiencing a surge in popularity as more consumers and SOHO users see it as the ideal technology to connect to the Internet and corporate LANs. One of the reasons for ISDN's popularity is the power it brings to Internet telephony due to its high bandwidth and flexibility. This technology's popularity is sure to increase with the introduction of Always On/Dynamic ISDN (AO/DI), a revolutionary new technology being implemented within ISDN that solves Internet telephony's "missing link," making voice over IP as easy to use as an analog telephone.

AO/DI provides ISDN users with a low-cost, continuous 9,600 baud connection to the Internet, notifying them when a call is coming through without the user having to pay the high tariffs associated with "nailing up," or leaving connections up and running for long periods of time using a traditional high-bandwidth connection.

ISDN provides the high-bandwidth pipeline to the Internet needed for voice over IP and now, with AO/DI, ISDN-based Internet telephony offers responsiveness and ease-of-use rivaled only by analog telephones.

A large problem for Internet telephony has been user availability. Because of the nature of the Internet, both par ties in a call must be logged on at the same time. This means that users must either prearrange calls or, to be available for unexpected calls, they must "nail up" a connection, leading to high phone bills.

AO/DI, proposed by the Vendor’s ISDN Association (VIA) late last year, uses the ISDN line’s always-active X.25 in the D-channel to provide the user with a constant connection to the Internet. With a throughput of 9,600 baud, this channel allows the user to be alerted to an incoming call; if the user chooses to receive the call, the modem activates one or both of the ISDN’s 64 Kbps B-channels.

Beyond AO/DI’s benefits to the end user, the new standard offers substantial benefits to both telcos and ISPs. As users and corporations increasingly demand continuous access to the Internet, telcos and ISPs have found their switches and routers increasingly bogged down by underutilized connections as users log on to the Internet or corporate LAN using an ISDN or analog line. With AO/DI, users initiate their B-channels only when receiving and transmitting data, allowing telcos and ISPs to make efficient use of networked bandwidth and support significantly more users on their existing networks.

However, even if AO/DI wasn’t offered as the only solution to the SOHO and consumers’ voice over IP connectivity needs, the other inherent technological benefits of wide band-width and integrated telephony features make ISDN an ideal solution for Internet telephony.

Internet telephony continues to gain importance as a better way to manage voice communications. As a result, improved Internet telephony software and solutions are causing users to expect higher audio quality. The weak link, however, is the lack of a sufficient physical connection between the computer and the Internet.

While large corporations access the Internet via digital T1 connections, most SOHO and consumer users are still driving the information super-highway in the analog lane. Unfortunately, analog connections, even using 56K modems, rarely exceed 33.6 Kbps — grossly inadequate to take advantage of the 80-90 Kbps speed available on the Internet. ISDN, on the other hand, offers throughput of 128 Kbps, more than sufficient to provide the high band-width needed to get the best voice over IP performance possible.

While promising new high-speed remote access technologies such as ADSL and cable modems are sure to impact the Internet telephony market, these technologies are not scheduled to be nationally deployed in this century. Additional drawbacks include an expected high cost in tariffing (versus ISDN), and lack of the telecommunications flexibility that ISDN provides (e.g., allowing the user to place/receive voice and fax calls over the digital high-speed connection).

That said, these new technologies do promise access to the Internet at higher speeds than ISDN, and the market will continue to evolve in this direction. However, at least for the next few years, ISDN is seen by some as the only viable high-speed remote access solution that is nationally deployed and stable enough to maximize the benefits of today’s cutting-edge Internet telephony products.

There is one more argument for ISDN: It is an integrated telephony solution, not limited to the Internet. Individuals still use analog connections for local calls, crucial long-distance calls, and fax transmissions — and ISDN allows them to use the same line and modem for both their telephony and Internet access needs. This is the "integrated" in Integrated Services Digital Network, and another reason why ISDN is perfect for small or home offices.

With ISDN’s integrated telephony features, users are able to use their ISDN line not only for a high-speed digital connection to the Internet or corporate LAN, but also as a way to initiate and receive telephone calls and faxes over the same ISDN line. ISDN modems provide POTS service over the digital ISDN connection. ISDN allows users to place phone calls with the broadcast quality connection of a digital interface. Also, ISDN provides advanced calling features found on telephones today, including call waiting, caller ID, three-way (conference) calling, and call forwarding.

An additional feature of ISDN that makes it incredibly flexible is its ability to provide Internet and analog connectivity at the same time. One B-channel can be used to connect to the Internet, while the other is used to send or receive a fax or telephone call. Additionally, ISDN is dynamic. This means that if a user is on the Internet using both B-channels (at 128 Kbps) and someone dials the user with a telephone call/fax, the ISDN modem will bump the Internet connection to one B-channel (64 Kbps) and receive the fax on the other B-channel. Once the fax is terminated, the Internet connection resumes its full two B-channel connection of 128 Kbps.

All told, the fully-integrated suite of telecommunications options delivered by ISDN makes it ideal not only for voice over IP, but as a powerful telephony solution for SOHOs and consumers who have a single ISDN line and modem.

ISDN devices have also become easier to configure with new ISDN technologies such as Auto-SPID and Auto-Switch. SPID stands for "service pro file identifier" and is a number provided by the telco that identifies your ISDN device to the ISDN line. Since SPIDs are only needed in North America and their use is the root of many of the problems and inconveniences in configuring an ISDN device, the term has jokingly been referred to as "Severe Pain In Deployment." However, SPID configuration is becoming easier with Auto-SPID and Auto-Switch technologies. Auto-Switch detection automatically analyzes the protocol for each telecom provider’s switcher. Auto-SPID, currently being implemented nationwide, is a protocol that the ISDN modem uses to automatically negotiate the ISDN line’s SPID numbers with the switch, without any user interaction. With Auto-SPID, the user simply plugs the modem into the ISDN jack; the modem then automatically configures itself without even being connected to a PC. The user simply plugs a phone into the port of the terminal adapter and places their first phone call within one minute.

Voice over IP will continue to grow as the most flexible and economical solution to managing long-distance and international voice connections. ISDN, with its high bandwidth, flexibility, and new innovations such as AO/DI and Auto-SPID, is quickly and rightfully emerging as the corporate and consumer interface of choice for Internet telephony. It is also the only affordable high-bandwidth solution that is being deployed nationwide.

Peter Geier is Eicon Technology’s ISDN marketing manager for the Americas with over eight years of international ISDN experience. Eicon Technology Corporation is a worldwide provider of remote access solutions for personal computers. The company develops, markets, and supports hardware and software products for connecting PCs to the Internet, corporate networks, and host computers. The products are sold in more than 70 countries through an extensive distribution network. Eicon Technology shares are traded on the Toronto Stock Exchange and the Montreal Exchange under the symbol EIC. For more information, visit the company’s Web site at www.eicon.com.

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