ISDN: The Future Of Internet Telephony
BY PETER GEIER
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.
A REVOLUTIONARY TECHNOLOGY
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 Vendors ISDN Association (VIA) late last year, uses the
ISDN lines 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 ISDNs 64 Kbps B-channels.
Beyond AO/DIs 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 wasnt 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.
MAXIMUM BANDWIDTH AVAILABILITY
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 todays cutting-edge Internet telephony products.
FULL TELEPHONY PACKAGE IN A SINGLE MODEM
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 ISDNs 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.
AUTO-SPID
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 providers switcher. Auto-SPID, currently being implemented nationwide,
is a protocol that the ISDN modem uses to automatically negotiate the ISDN lines
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.
CONCLUSION
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 Technologys 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 companys Web site at www.eicon.com.
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