-- by Cynthia Morgan
Take a deep breath, grit your teeth and activate the device. Then, say a prayer to the ISDN gods and start the call. If you're lucky, your new ISDN device connects the first time. If not, welcome to the world of ISDN configuration.
We've come a long way from the days when ordering ISDN meant first tutoring the phone company representative. My initial order a few years back was met with, "But dear, you don't need an SDI-whatchamacallit; you just go out and buy an m-o-d-e-m."
Installation horror stories still abound, but ordering ISDN is now a fairly routine request in most metropolitan areas. Getting ISDN to work on your PC, however, still ranks as an arcane art. I recently tested four ISDN terminal adapters (TAs) that ran the gamut from a simple $239 ISDN unit to a $619 telephony/fax modem system for notebook computers. (For a look at Jetstream's Front Desk ISDN 1.0, a high-end ISDN telephony system, see the Reviews section.) Only one, U.S. Robotics' Courier I-Modem, worked perfectly on the first try. The remaining three eventually made at least single-channel (64Kb per second) connections to my ISP and WINDOWS Magazine's lab network, but only after multiple unsuccessful attempts.
Connectware's PhoneWorks ISDN Ext offers an attractive aerodynamic design. I thought of this when I wanted to toss it across the room after repeated connection failures. The competent support technician I spoke with finally suggested the PhoneWorks' bewildering insistence on a dataless, voice-only mode was due to a reset failure. I overcame this by repeatedly restoring defaults, rebooting and restoring again. The PhoneWorks is now aggregating (combining) both B channels like a champ. It consistently provides the fastest transmission times of all four devices, and at $239 it's an exceptional value.
If you'd like to combine fast Web surfing with a digital answering machine/phone system, this unit and Connectware's $619 PhoneWorks ISDN+ To Go PCMCIA modem both offer telephony features. They come with comfortable headsets, and phone dialer and address book software. They automatically step down from full two-channel access to a single 64Kbps data line and digital telephone.
PhoneWorks ISDN+ To Go is also a fax modem, with an additional connector for analog. I was disappointed to find its modem speeds limited to 28.8Kbps; an upgradable 33.6Kbps would have been nice, especially given its price.
ZyXel's Omni TA128 ISDN terminal adapter offers a feature small-office or home users should appreciate. Two computers can use the device at the same time over a single ISDN line. Each computer can use a single B channel for voice or data transmissions. But the Omni proved stubborn about making V.120 connections, and had some trouble aggregating channels to increase speeds. It took repeated installations and resetting of Windows 95 dial-up connections to get it to talk to my ISP's line. Although it's working smoothly now, I'm not looking forward to reinstalling it on other systems. The Omni installation software does offer one feature all ISDN devices should provide: the ability to manipulate direct AT commands right from the configuration window.
U.S. Robotics' Courier I-Modem is a truly multifunction device. It offers an analog connection port for fax machine or telephone, and automatically steps through digital and analog speeds until it connects. A USR spokesperson said the analog side of the device would soon be upgradable to the new 56Kbps modem standard announced in late 1996.
To install the Courier, I simply plugged it in and booted it up alongside the PC. Win95 autodetected it, asked for configuration disks, and ran a configuration manager to install SPIDs, DNs and protocols. It took only 30 minutes from opening the box to making my first ISDN call, less than half the time it took for the next-easiest installation, the PhoneWorks ISDN+ To Go card.
I'm a sucker for external modems; with online and ISDN charges calculated by the minute, I like to know when I lose a connection or freeze a download. The Courier gave me all the LED indicators I needed. ZyXel's Omni grouped and labeled its status lights sensibly, and its external reset button was helpful during installation. The PhoneWorks Ext unit offered only two external indicators-a power-on light and connection LED that blinked during an ISDN call. This is only slightly more convenient than an internal device.
All four devices represented considerable performance improvements over my 28.8Kbps fax modem. I tested relative throughput by uploading and downloading a 6MB file, a task that averaged 67 minutes at 28.8Kbps. Switching to two-channel ISDN-115.2Kbps-lowered that time to 21 minutes; adding data compression and a fast serial card slurped up all 6MB in about 12 minutes.
My advice? If you're switching to ISDN, read the installation manual carefully before you start, make sure your phone company documentation is on hand, prepare for a long night ... and buy the Courier.