San Diego - A new twist on ISDN that takes advantage of the underused D channel could reward customers with lower remote access costs by year-end.
But that will depend on how much carriers charge for Always-On Dynamic ISDN (AO/DI), a new offering that relies on Basic Rate Interface ISDN's D channel to provide low-bandwidth, dedicated packet links.
The ISDN offering, to be promoted this week by carriers and hardware vendors at the North American ISDN Users Forum and ISDN World here, would let users run e-mail and other low-speed applications on the 16K bit/sec D channel. This channel is capable of moving about 9.6K bit/sec of X.25 packet data while also handling its conventional signaling chores.
Today, most ISDN customers send data over one or both 64K bit/sec Basic Rate Interface B channels only, regardless the transfer size. The drawback for customers is that many carriers bill for B channels by the minute.
With AO/DI, one or both B channels can be turned on when really needed, such as to support videoconferencing or other high- bandwidth applications.
When a remote end user with AO/DI hardware logs on to his or her terminal, the AO/DI gear would establish a switched virtual circuit (SVC) connection to the corporate network or an Internet service provider that also supported AO/DI. The SVC would stay nailed up until the customer logs off, allowing the customer to receive data forced along by push technology or access the corporate LAN.
Using the D channel to send data is not an entirely new concept. However, the hardware that currently supports D channel data communications is geared specifically to connecting retailers to banks for credit card checks.
The service is priced on a per-packet basis that would prove prohibitive to users of most other applications.
Rewriting the tariffs that set the price for sending packet data over the D channel will determine the success of AO/DI, according to Jim Bryce, a member of the Texas ISDN Users Group.
Most of the regional Bell operating companies said they were working on pricing, and some expected to have new tariffs filed by the end of the year, around the time hardware vendors figure they will have AO/DI-compliant gear ready.
BellSouth Corp. will run trials later this month in Birmingham, Ala., using Cisco Systems, Inc. equipment to determine the impact that widespread use of AO/DI would have on BellSouth's packet- and circuit-switched networks.
Pacific Bell has plans to offer an ISDN hardware/service bundle.
