TESTING BY MARK BAYNES
US Robotics' (USR) x2 modem technology, which provides a 56Kbps transmission rate, may well be the last gasp of the traditional analog modem. The fact that 56Kbps is only possible in one direction and is dependent on having the appropriate technology at the other end of the line would seem to be proof of this. It is interesting therefore that USR has decided to cover all possible bases with the launch of the Courier I-Modem - a single internal card which is both a V.34 analog modem and a Basic Rate ISDN card - and should have x2 technology support bundled sometime in January/February 1997.
Traditional modems are getting faster, but these increases in speed are incremental - the reality is that the modem is reaching the limits of what is possible with analog technology. It is no surprise, then, that coupled with the reduction in BT's tariffs for Basic Rate ISDN access, we are seeing a shift towards Basic Rate for homeworking, remote access and leased line backup.
The I-Modem is a full length ISA card which has one jack for a Basic Rate ISDN line and one for a standard PSTN line in its rear bracket. It also has a small red box containing four DIP switches; two of which are not used; the other two are for telling the card whether to ignore or act on AT commands and loading NVRAM settings. The card has an Intel 386EX chip, DSP unit and ringer unit at the rear. The card was easily installed into an ISA slot on a 100MHz Pentium PC.
Windows 95 is a surprise inclusion
Included with the I-Modem is an ISDN cable, a quick reference card, Getting Started manual, Reference manual, the almost obligatory free trial AOL membership (which went straight in the bin), and a manual for the bundled QuickLink II comms software (which will go in the bin).
To find Windows 95 drivers included with an ISDN card is still a rarity, as for many ISDN card and TA manufacturers Windows 95 support is very much an afterthought. If your system is plug-and-play then you simply specify this using the J29 jumper and any settings on the J28 jumper are ignored. Your system should auto-detect the card and all you have to do is supply it with the Win95 driver disk if required. The IRQ and Com port settings are configured using two banks of jumper switches at the bottom of the card, but these are difficult to get to if the card is in place.
For manual installation you must first run the Comtest utility from the QuickLink II disk which can either suggest IRQ and Com port settings, or test an already installed I-Modem. The IRQ and Com port settings then must be set and here lies a small, but potentially irritating, problem - the documentation on the Quick Reference card and in the Getting Started manual differs as to where to put the jumper for the IRQ 3 setting. This caused problems, but USR's technical support suggest you follow the Quick Reference card.
The next task is to install the ISDN configuration software onto the hard drive and then configure the I-Modem. This is done from one screen and the main item of relevance is the switch type which should be set to ETSI NET3 (Euro-ISDN) for UK ISDN.
The next setting is the Call Type which is where the I-Modem can come into its own. If this is set to Automatic Service Choice it will first try to connect using V.120 rate adaptation. If this connection fails it will try V.110 adaptation and then will revert to the analog modem at V.34 and try to connect at whatever speed possible.
Ideal for remote nodes on the move
Other possible settings for Call Type are Internet access (tries to make a PPP connection and if this fails reverts to modem mode), Clear-Channel Synchronous where it sets up a clear 64kbps channel with a remote device, V.120 Rate Adaptation, V.110 Rate Adaptation, and analog modem or fax.
Bonding the two BRI channels will be available in late January/February.
The Courier I-Modem may be the ideal solution where you have a number of remote nodes which are using PSTN for dial-up connections to a central office but will be migrated to Basic Rate in the future.
Product: US Robotics Courier I-Modem
Availability: US Robotics (01734) 228 200
Price: #399 (Internal and external models)
Ease of Use: *****
Value for money: *****