Upgrade costs would offset savings from new ISDN technology, says Telecom

Telecom's ISDN network would support a new US technology aimed at lowering the cost of ISDN use - but businesses and ISPs still might not find it immediately viable, according to a spokesman. Always On/Dynamic ISDN (AO/DI) takes advantage of ISDN's D-channel - normally used for signalling between the service provider's switch and the customer premise equipment - to send low-speed data.

Telecom's ISDN network would support a new US technology aimed at lowering the cost of ISDN use - but businesses and ISPs still might not find it immediately viable, according to a spokesman.

The new technology - Always On/Dynamic ISDN (AO/DI) - was announced this week by the US Vendors' ISDN Association and the National ISDN Council. It takes advantage of ISDN's D-channel - normally used for signalling between the service provider's switch and the customer premise equipment - to send low-speed data.

The user's D-channel has an "always on" virtual connection to the switch, even when the user is not connecting over the higher speed B-channels. The D-channel can handle traffic at speeds up to 9.6Kbit/s, fast enough to send email, stock quotes, or news feeds.

Telecom media spokesman Quentin Bright says Graham Rowe, marketing manager of Telecom's computer communications unit, acknowledged AO/DI was "a great idea - but there would be some investment required for a lot of people. The most common ISDN routers - Cisco and Ascend - don't currently support the D-channel, so it would probably require new infrastructure on the part of ISPs to make it work. For example if you took an ISP which had existing infrastructure - some of the bigger ones around now - it couldn't be done because the Ascend gear doesn't recognise the D-channel for data transport.

"If you were a business person or an ISP you'd have to you'd have to weigh up the equation and say do I have enough ISDN usage to enable me to set up a satisfactory business case? Although arguably it's going to keep on growing. Your ISDN router would have to support the D-channel and also encapsulate TCP/IP into X.25 - and that's a very important part of it."

Cisco and Ascend are, however, members of VIA, and would presumably support AO/DI applications on that basis - as might Telecom itself if the technology delivers on the promise of satisfying customers' desire to be permanently connected without tying up lines.

"It would save you the cost of having to phone and see if you have messages, and it would also save the infrastructure the cost of having you call on the B-channel because you wouldn't need to do that," according to Deepak Kamlani, executive director of the VIA.

If a user moves to a high-bandwidth application, such as downloading a Web page with lots of graphics, AO/DI can automatically add the B-channels, which each run at speeds of 64Kbit/s, he says.

The D-channel charges will have to be set, but since it's a low-bandwidth service, they probably will not be "humongous," Kamlani says. In addition to lowering users' ISDN costs, AO/DI will reduce long hold-times on B-channels, which will ease a strain on the service providers' infrastructure.

"You'll always have access to the B-channel but you won't have it on all the time," Kamlani says. "So you won't have a bottleneck when you need to get through ... or be paying for the B-channel when you don't need to be."

Nynex Corp. demonstrated AO/DI this week at the North American ISDN Users' Forum meeting in Tampa, Florida, about six months after the VIA proposed the concept. Several vendors plan to release AO/DI upgrades to their ISDN customer premise equipment by the end of this year, which is also when service providers will begin offering the service, Kamlani says.

While the demonstration was in the US, there is no reason why AO/DI technology could not be extended anywhere ISDN is offered, Kamlani says. Basic Rate Interface ISDN, around the world, consists of two B-channels plus a D-channel.

Kamlani believes AO/DI will appeal to both work-at-home ISDN customers as well as people who use ISDN for Web surfing. The California ISDN User Group's chairman, however, believes work-at-home users with more sophisticated equipment will adopt it first, since they have the most to gain.

"One of the problems with ISDN is that you can't afford to be connected all the time," says Bob Larribeau of San Francisco, chairman of the California ISDN User's Group, who has four ISDN lines into his home for voice and data. "[AO/DI] lets you maintain a low bandwidth connection all the time without running up huge connection bills."

The Vendors' ISDN Association can be reached on the World Wide Web at http://www.via-isdn.org/.

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