Selecting an ISDN Terminal Adapter
----------------------------------

Q.  I'm waiting for my ISDN line to be installed.  How do I pick and
purchase the right ISDN adapter for my needs?

A.  There are a wide range of ISDN adapters available.  While standards
have solidified somewhat and interoperability has improved, it is still
important to ensure that the adapter you choose is capable of working
with the ISDN routers that Northwest Nexus uses to provide service.

Northwest Nexus maintains a list of ISDN devices that it has certified
as interoperable and supportable.  We strongly recommend that you choose
one of the devices on this list.  We regret that we can not provide any
support whatsoever for customers using devices not on the certified list.

If you have not already done so, we strongly recommend that you obtain
and review the other FAQs in this series; see the end of this document
for a list of the available FAQs.


Q.  Where do I find the list of certified ISDN devices?

A.  If you have access to the World Wide Web, visit

    http://www.nwnexus.com/isdnserv.html
    
If you do not have access to the Internet, contact Northwest Nexus sales
staff toll-free at 1 888-NWNEXUS (1 888 696-3987).


Q.  Does Northwest Nexus sell ISDN adapters?

A.  Service packages are available that include ISDN adapters as part of
the one-time setup fee.  Contact a Northwest Nexus sales representative
for details.


Q.  What should I look for in choosing an ISDN adapter?

A.  The following should be considered in choosing an appropriate ISDN
adapter:

    - Inclusion on the Northwest Nexus certified list
    - Ease of setup, programming, and maintenance
    - Availability of required interfaces
    - Local interface bandwidth capacity

    
Ease of Setup, Programming, Maintenance
---------------------------------------
Northwest Nexus will pre-program ISDN adapters purchased from Northwest
as a part of the service set up fee.  Nevertheless, it is possible that
you may need to make minor adjustments to your router as you install it
or in the event you make changes in your local network.

Farallon offers their "Netopia ISDN Modem," whose interface is simple
and straightforward.  The Netopia ISDN Modem is virtually identical to
3Com's "ImpactIQ ISDN Modem," differing only in the software included
and case color.  Both devices are capable of configuring themselves once
you connect them to your ISDN line, turn them on, and enter your ISDN
directory numbers.

The above devices are all external devices with their own power supply.
Internal bus cards are available for Windows, NT, and Macintosh
platforms; these devices have some advantages in integration and
usable throughput, but all of them are considerably more complex to
install and configure, with switches, jumpers, and interrupts to
set.

Availability of Required Interfaces
-----------------------------------
In most cases, an ISDN terminal adapter includes an asynchronous serial
port, for connection to IBM PC compatible or Macintosh serial ports, or
to any system that has a serial port.  Because these devices have
modem-like command interfaces, they can be used with any operating
system that or communications program that supports the Hayes AT-command
set and PPP protocol. ADTRAN's Express XR and XRT terminal adapters have
similar features and ports.  The Farallon modem is available in PC and
Mac versions, with serial port connectors and software appropriate to
each platform.

All three of the devices mentioned have configurations available that
include two POTS jacks for use with standard telephone sets.

Internal ISA bus cards are available for the PC, and NuBus cards are
available for the Mac.  The Digi Datafire card for Windows and NT
systems is Microsoft's favored ISDN adapter.  The USR Courier I-Modem is
one of the easier to install ISA bus cards, and includes a "V.anything"
analog modem and ISDN terminal adapter accessible through the same COM
port and using a single IRQ. The Datafire card does not include a POTS
jack; the I-Modem includes a single jack.  These and other internal ISA
bus cards require the installation of special software drivers, or in
the case of systems running Windows 95, the installation of Microsoft's
ISDN Accelerator Pack V1.1.

If you're using Windows 95 and intend to choose an internal ISDN adapter,
be certain to visit Microsoft's excellent ISDN pages at

    http://www.microsoft.com/windows/getisdn
    
There are excellent (and lengthier!) descriptions of everything you've
read in these FAQs at the same Web location.  Highly recommended if
you're of the Windows persuasion.

External ISDN adapters have the advantage of being platform-nimble
(and therefore more easily resellable when you upgrade).

Local Interface Bandwidth Capacity
----------------------------------
Because these ISDN adapters connect to a single computer using a serial port,
it's important that the computer's serial port be capable of speeds that
can accommodate the 64kb/s or 128kb/s bandwidth that ISDN adapters can
provide.  For IBM-compatible PCs running Windows, this means that the
serial ports must use 16550 UARTs and, for Windows 3.x systems, that a
third-party serial driver capable of taking advantage of the 16550 UART
be installed.  Even with all this, you may still find your system
incapable of taking advantage of the full 128kb/s bandwidth available.
For the Macintosh, one must have a later-model Mac with a fast serial
port, and even then, one might have difficulty reaching 128kb/s
throughput.

If you want to easily get the full 128kb/s speed from your ISDN
connection, you might consider Ascend's Pipeline 25-PX.  This adapter
offers an Ethernet 10baseT interface that connects to your system's
Ethernet card.  The P25-PX works with Northwest Nexus Dial-Up ISDN
service and its server-assigned IP address.  Despite the Ethernet
interface, the P25-PX supports only a single computer at a single IP
address.  It is a simple, full-speed ISDN solution for use with Dial-Up
ISDN, and requires only that you obtain and install an Ethernet card. 
These days, on Macintosh, Windows, and other systems, that's relatively
easy, and not more expensive than about $100.

Farallon's Netopia ISDN Routers also come with a similar feature, called
Network Address Translation, but is somewhat more capable.  NAT, also
called Smart IP, uses a mapping scheme to allow a Dial-Up ISDN
connection with a single server-assigned IP to be shared among a number
of machines (up to 12) on an Ethernet network.  Each machine can access
the Internet, but the IP address for each machine is known only on the
local Ethernet, thus enhancing security.  Using a port-mapping scheme,
it is possible for nodes on the Internet to access different servers,
such as a Web server, telnet server, or SMTP mail server, on your local
Ethernet.  Farallon does an excellent job of providing the most bang on
an inexpensive Dial-Up ISDN connection, and makes the higher-than-the-
P25-PX price of the device worth it in some applications.  The Netopia
solution also provides an excellent upgrade path; if you later want to
switch to a Dedicated ISDN connection, you can use the same box, instead
of having to purchase an ISDN router.  The Pipeline, in contrast, is not
upgradeable to a full router.


Q.  What ISDN devices do you recommend for Dial-Up ISDN service?

A.  For maximum throughout and relative ease of setup, Ascend's
Pipeline P25-PX, combined with an existing or added Ethernet
10baseT card, is a handy reasonably priced choice no matter which
hardware or operating system you're using.

If you need to provide Internet access to more than one node on a local
LAN using a Dial-IP ISDN connection, or you expect to someday upgrade to
a full-time, fully routed ISDN connection, the Netopia ISDN Router is
the clear choice.

If you prefer an internal card and you need a V.34 analog modem
(upgradeable to 33.6kb/s and 56kb/s technologies), USR's Courier I-Modem
is a reasonable choice and provides a single POTS jack.  Be prepared for
downloading software from Microsoft, obtaining updated drivers from USR,
setting DIP switches and debugging IRQ conflicts, along with removing
your current internal analog modem, if you have one.  Remember that you
can't use the POTS jack if your computer is turned off, nor can you use
the ISDN adapter for an Internet connection at the same time you send a
fax over the analog modem portion of the card.  And you'll have no
visual indication of ISDN status, or indication at all that you're using
two channels beyond an easy-to-miss beep.

For easy external ISDN connections via an upgraded fast serial port,
both the Farallon Netopia ISDN Modem and 3Com ImpactIQ are excellent
choices, providing easy configuration and two POTS jacks.  The Netopia
ISDN Modem comes with a more extensive software package, including a
two-license version of Farallon's excellent Timbuktu Pro remote
control software, so it's the preferred choice of the two external
ISDM modems.

      
Q.  Where can I find out more about the ISDN devices you've discussed?

A.  Here are Web pages with comparison charts for the routers discussed
    in this document

    Farallon Communications Inc.
      Netopia ISDN Modem
        http://www.farallon.com/product/netopia/netmover.html
    
    3Com Corporation
      ImpactIQ External ISDN Modem
        http://www.3com.com/0files/products/dsheets/dsmt5.html
    
    Ascend Communications Inc.
      Pipeline P25-PX
      http://www.ascend.com/products/pipelinefamcompare.html
      
    ADTRAN Inc.
      ISU Express XR and XRT
      http://www.adtran.com/cpe/isdn/isu.html 
      
    Microsoft's Windows ISDN site
      Excellent guidance on choosing the right hardware and ISDN in
      general
      http://www.microsoft.com/windows/getisdn  
      
      
Q.  Where can I purchase the ISDN devices you've discussed?

A.  Northwest Nexus offers selected ISDN devices packaged with ISDN
service. Contact the Northwest Nexus sales department toll-free at 1 888
NWNEXUS (1 888 696-3987) or via e-mail at sales@nwnexus.com.

If you are comfortable with mail-order or ordering via the Internet,
many of our customers have found a reliable overnight source of many
ISDN products in

    Data Comm Warehouse
    1 800 328-2261
    http://www.warehouse.com/DataComm/	
    
If you'd prefer a local supplier in the Western Washington area, you might
try

    Network Computing Architects Inc. (NCA)
    Bellevue, Washington
    1 206 455-4520
    http://www.ncanet.com 
    
Both COMP/USA and Computer City, with locations throughout Washington and
Portland, stock a number of ISDN terminal adapters.
  

Q.  What number do I tell my ISDN adapter to use to contact Northwest Nexus?

A.  A chart of the available ISDN access numbers is available on the Web at

      http://www.nwnexus.com/phones.htm
    
    
Q:  Am I done yet?  What do I do next?

A.  Obtain and review the appropriate "How to Configure..." FAQ for the
ISDN adapter or router you have chosen.  The complete set of ISDN FAQs
includes the following titles:

	ISDN for Home or Business:  An Introduction and Brief Orientation
    (ISDN basics)
  ISDN Glossary
    (ISDN-related terms, acronyms and definitions)
	Establishing ISDN Service with Northwest Nexus
		(how to order, install ISDN service)
	Selecting an ISDN Terminal Adapter
		(the FAQ you are reading)
	Selecting an ISDN Router
		(how to select, overview on install and setup)
	Configuring Your ISDN Terminal Adapter
	Configuring Your ISDN Router
		(specifics on adapter configuration and software setup)
	Debugging ISDN 
	  (general debugging tips)


Q:  How can I stay up to date on ISDN developments at Northwest Nexus?

You can keep abreast of ISDN at Northwest Nexus by subscribing to one of
our ISDN mailing lists, or by participating in our ISDN newsgroup.

Our ISDN mailing lists are low-traffic, one-way e-mail lists that
contain ISDN-related and news, announcements, and tips.

If you're a Northwest Nexus customer, you may join the isdn-interest
list.  If you're not yet a customer, subscribe to isdn-announce.  Both
lists get news of our latest ISDN products and offerings.

To subscribe, send an e-mail message to majordomo@halcyon.com

In the body of the message, include these two lines:

	subscribe isdn-interest
	end

or

	subscribe isdn-announce
	end


Northwest Nexus also maintains a newsgroup for our users to discuss ISDN issues,
share tips, and troubleshoot problems.  Use your browser or a newsreader and
subscribe to

	halcyon.isdn
	


[1Apr97/MJT]