Here's How to Get Ultrafast Connections to the Internet -- or to Other Users.
Henry Norr
Ever since ISDN -- the Integrated Services Digital Network -- was defined more than a decade ago, wags have joked that the acronym really means something I Still Don't Need. It Sounds Darn Nice, they say, but It Still Does Nothing. In recent years, though, the reality has been changing.
Users are starting to realize that ISDN can be a cost-effective solution to a variety of communications challenges: moving huge graphics and multimedia files between service bureaus and customer sites; giving telecommuters quick access to the corporate network; and speeding access to the World Wide Web. The regional Bell telephone companies are finally getting the message: They're offering the service in more locations, slashing tariffs, and learning to explain to their customers what the technology is all about. Today, in fact, you could say of ISDN that It's Steadily Developing Nationwide.
The companies that make the hardware you need in order to put ISDN on your desktop are responding too: They're delivering new products, trimming prices, and making installation easier. Companies that have Mac backgrounds, such as Farallon Computing and 4-Sight -- and even Apple -- are jumping into the ISDN market, and other vendors are starting to pay more attention to Mac users. Altogether, It's Surprisingly Doable Now.
Be prepared, however, to invest some time and effort in planning; setup; and, more likely than not, debugging. The jargon is daunting, the choices are many, and interoperability isn't guaranteed. In short, Investigation's Still a Dire Necessity and Installation's Still Depressingly Nerdy. But this primer can at least help you understand and evaluate the options the experts lay out.
Question 1: What Is ISDN, Anyway?
Without getting into all the geeky details, ISDN is a set of protocols that make it possible to implement a wide range of digital communications services over the twisted-pair copper wire that links most homes and offices to the worldwide telephone grid. ISDN's advantage over conventional voice, fax, and modem communications lies in its digital nature. Although most of the backbone that carries telephone traffic around the world has been digital for years, in the U.S., the last link -- the connection between the user's equipment and the phone company's switches -- normally continues to carry information in analog form (sounds, in a word). That limits both flexibility -- how many things you can do at once with a single line -- and performance -- how quickly you can transfer data.
By making communications digital from end to end, ISDN breaks through the analog bottleneck. When all data is in digital form, even a conventional copper-wire hookup has enough bandwidth to carry on several jobs at the same time: The standard ISDN setup for small offices and homes provides two separate logical channels for user-generated data plus a separate channel for control signals between your site and the phone company's switch. This means that with one ISDN line, you can receive a fax through one channel while surfing the Net through another or you can chat with Aunt Sally in Peoria while downloading the file of the month from ZD Net/Mac. (In ISDN jargon, this kind of entry-level installation is called a basic-rate interface, or BRI; the two channels available for your data are bearer, or B, channels, and the control line is the delta, or D, channel. The next step up in bandwidth, called a primary-rate interface, or PRI, provides 23 B channels and 1 D channel.)
Eliminating the need for an analog modem also makes data transfers faster. Although state-of-the-art V.34 modems can push through up to 28.8 kbps of data, ISDN is designed to handle 64 kbps bidirectionally -- on each B channel. (In California and some other areas, each B channel is limited to 56 kbps, because of how Pac Bell handles signaling among switches, but that should soon change.) For large data transfers, many ISDN devices can combine the two B channels, for an effective rate of 128 kbps (112 kbps in California). In real life, of course, some of this goes for overhead, but that's true for conventional transfers as well as for ISDN; likewise, with both technologies, data compression can increase effective throughput.
A key feature of ISDN, in contrast to competing technologies such as leased lines or frame relay, is that it works on demand: Your connection is activated only when you need it, so you pay only for the time you're online. (Some phone companies and Internet providers, however, offer 24-hour-a-day ISDN service plans, even though the technology was really designed for intermittent connections.)
Someday ISDN bandwidth will look puny, but the Next Big Thing is likely to involve expensive new technology and/or fiber-optic cabling all the way to your doorstep. The beauty of ISDN, especially from a cost point of view, is that it uses the existing phone grid, including the copper wiring that runs right to and through your home or office. (Hooking up ISDN is often referred to as "installing a new line," but unless your current lines are maxed out or in unusually poor condition, you won't need new wiring; "installation" usually means just tuning up your current connections.)
Question 2: Does ISDN Replace My Phone Line?
It's up to you. With the right hardware, you can use an ISDN line for voice and fax communications plus computer data. All you need (unless you want expensive phones or fax machines designed for ISDN) is to make sure your ISDN adapter has at least one RJ-11 jack (see the "Hardware Checklist" sidebar); then plug in your phone or fax machine, and you can use either over ISDN. If you disconnect one or more of your phone lines, the money you save may quickly cover the cost of your ISDN hardware. (And you'll get a slew of new telephony features, with support for up to eight devices on one line.)
There are good reasons, though, to consider leaving at least one conventional line in place. It often takes some time to get a new ISDN connection running smoothly, and you probably don't want to depend on it for all your communications needs during the shakedown phase. Even when it's running smoothly, one ISDN line may not suffice: If you're talking on one channel and surfing the Net on the other, someone trying to send you a fax will get a busy signal. Finally, there's a safety issue: If the power goes out, a conventional phone will normally keep working but your ISDN line will go dead.
Question 3: Are There Restrictions on What I Can Connect to via ISDN?
No, you can call any number -- be it voice line, fax machine, Apple Remote Access server, online service, BBS, or Internet provider -- over an ISDN line. But -- and here's a critical point that's often misunderstood -- you can make a true ISDN connection, with the resulting performance boost, only when the service you are calling also has ISDN. If the service at the other end does not have ISDN, all you are doing is using an ISDN B channel to carry a digitized version of the analog signals your modem generates. In other words, if you're running a prepress service bureau and exchanging Photoshop files with your clients seems to take forever, even with V.34 modems, having ISDN at your end alone isn't a solution -- you'll need to make sure your major customers also get it. And if you want to speed up graphics-rich Web pages, you may have to switch Internet service providers if yours doesn't offer ISDN.
With online services, the picture is more complicated. At this writing, none of the major services offers direct access via ISDN, but CompuServe and America Online have announced plans to do so by the end of 1995. Check with the service you use to find out when your city will get the service and how much it will cost.
Question 4: How Much Speed Will I Really Get from ISDN?
Compared to an analog modem, ISDN is extremely fast: Just a single B channel offers about twice the throughput of a V.34 modem; if both channels are working on the same file transfer, you'll have more than four times the bandwidth of the speediest dial-up connection.
It's important, however, to keep the proper perspective: 128 kbps, the maximum bandwidth for a standard ISDN BRI connection, still falls well short of even LocalTalk speeds (theoretically, 230 kbps). A speed of 128 kilobits per second translates into a speed of 16 kilobytes per second, or 960 kilobytes per minute. (If you are in California, you should reduce these numbers by one eighth.) In other words, ISDN's maximum transfer rates are well under 1 megabyte per minute.
And then there's real life: If your ISDN adapter is one of the numerous models that aren't able to bond the two B channels together or if you are using an external adapter on a Mac that doesn't have a GeoPort, cut those rates in half. If you're running ARA, you can expect some extra overhead that will slow you down further. If you're surfing the Net, remember that no amount of bandwidth at your end is going to solve the problem of overloaded servers and routers: Jumping to a new location still takes time, and your Web browser may come to a screeching halt with a graphic half drawn if the server you're connecting to is busy dealing with other users' requests.
In short, if you're someone who thinks that digital communications means downloading huge files in seconds or watching full-screen movies in real time, you're in for a disappointment. But if you put fantasy aside and compare ISDN with any other communications technology available today affordable for home or small-business use, it looks very good indeed. One easily overlooked benefit, by the way: Establishing a connection over ISDN, including a password log-in, normally takes less than five seconds -- and you don't have to listen to the squeals and moans of mating modems.
Question 5: How Much Does It Cost?
Installation fees, monthly service charges, and metered call rates for residential and small-business ISDN service vary widely by region, and they're changing fast, so you'll have to check with your local phone company (see the "Resources" sidebar). California's Pac Bell appears to be setting the pace: For home users, all but $34.75 of the installation fee is waived if you keep the service two years; monthly charges are only $24.50; daytime local calls cost 4 cents for the first minute and a penny per minute thereafter, but they're free outside business hours. For long-distance ISDN calls, your choice of carriers may be limited and the rates higher than you're used to; if you plan to do a lot of long-distance dialing, check carefully in advance.
If you want to tap into the Internet, you'll also need to sign up with a service provider that offers ISDN access in your area. Since most providers are not yet up on ISDN, you won't have as many choices as you do for a 14.4- or 28.8-kbps dial-up account and you may end up paying higher rates. But most providers that do offer ISDN don't charge a huge premium: Typical rates are on the order of $30 per month for 30 hours of usage.
The largest up-front expense is the ISDN interface for your Macintosh. Here as well, the prices are dropping, but as of this writing, in the middle of 1995, you can figure on paying a minimum of $400 for an adapter. And remember that options costing two or three times as much may actually be more cost-effective in the long run.
Some phone companies now have specially trained ISDN service reps who can offer advice on your hardware and service options; the Internet service provider you plan to work with may also be helpful. But if you're having trouble getting a straight story, or if the reps you talk to keep suggesting ISA cards no matter how often you say "Mac," or if you want to implement advanced telephony services such as fax-back, you may want to factor a consultant's fee into your budget. Don't go to just any computer or communications consultant, though -- you need someone who knows both the Macintosh and ISDN. Alternatively, if you have little time or interest in fiddling with communications technology, you may want to consider a turnkey system, such as one offered by 4-Sight. You'll pay a substantial premium, but in exchange you'll get an integrated package, including special software, and some place to turn if -- and when -- problems arise.
Question 6: What Are My Hardware Options?
Basically, you have three kinds of hardware to choose from, with several options in each category. Each alternative has pros and cons, depending on your needs and your budget.
External Serial-Port Device. The simplest and least expensive hardware to install is an external box, known in ISDN jargon as a terminal adapter, or TA, that attaches to a serial port on your Mac and to your ISDN wall jack. This device looks and (from the user's point of view) acts like a conventional modem; some vendors even call it a digital modem, although technically that term makes no sense. Popular models include the 3Com Impact (formerly known as the QuickAccess Remote) and the Motorola BitSURFER. By the time you read this, Apple may have joined the fray with an ISDN pod for the GeoPort, the high-speed serial port in the Quadra AV family and most Power Macs.
The most obvious advantage of a TA is price: less than $500 and headed lower. Another benefit is simplicity: Because it looks like a fast modem to your software, you don't need special software -- existing telecom applications and drivers such as MacPPP should work, although you may have to fine-tune your modem-initialization strings. (You'll need a special script for ARA. 3Com includes one; Motorola does not.) Finally, a serial-port adapter offers plenty of flexibility: You can easily hook one up to any Mac (including a PowerBook) or PC.
On the negative side of the ledger, this device requires a serial port -- a problem if you have a LocalTalk network or printer and a conventional modem for calls to non-ISDN sites (not to mention a Newton, a Connectix QuickCam, or a Visioneer PaperPort). Installing a serial-port card can solve the problem, but at a cost of $200 to $300. You can also use an A/B switch, which costs as little as $20, but having to remember to flip a manual switch to use your expensive digital equipment can be frustrating. In addition, if both ISDN B channels are bringing data to the Mac simultaneously, the serial port may become a bottleneck.
Internal Adapter Card. Instead of the serial port, an internal adapter uses the computer's expansion bus to transfer data between the Macintosh and ISDN. Several companies manufacture NuBus ISDN cards and more are expected for the PCI bus, but no ISDN cards are available for PDSs (processor-direct slots). An internal card has three primary advantages: It saves you space on your desk; it avoids the risk of encountering serial-port bottlenecks; and it lays the groundwork for future multicard setups, such as a videoconferencing system built by linking ISDN and video-capture and -compression cards.
Using a card has disadvantages, though: A card is not easily transferable to a new machine. It requires special software drivers, with the attendant risk of bugs and conflicts. And, at least in the NuBus era, a card has been more expensive than an external device -- the most common card, the Planet II, from SIT/SAGEM (formerly Euronis), costs $800 to $1,000.
Ethernet Router. The alternative is to employ a router to connect ISDN and an Ethernet network. The big advantage of this approach is its transparency. You don't need special software or hardware in your Macintosh -- just standard network drivers with either an Ethernet card or a built-in port; the router takes care of the ISDN communications. In terms of user experience, if a terminal adapter (external or internal) feels like a fast modem, router-based ISDN feels like a direct TCP/IP connection (albeit slower than what you may be accustomed to at work or on campus). The Internet becomes an extension of your LAN: Just click on a URL in Netscape Navigator or tell Eudora to check your mail, and in seconds you're racing down the information highway. Routers additionally provide maximum speed, because communications protocols and (in several models) on-the-fly data compression are implemented in hardware and Ethernet provides plenty of bandwidth, even to older Macs.
At first glance, cost appears to be the biggest disadvantage of the router approach: Prices for stripped-down models have only recently dropped below the $1,000 mark, and full-featured units such as Ascend Communications' Pipeline 50 and Combinet's Everyware 2000 list for more than $1,500. For a single user, that adds up to a stiff premium. But if more than one person at your site requires ISDN access, the picture looks very different, since everyone on a LAN is able to share the same hardware and ISDN line at no additional cost (although your Internet provider will probably charge more for providing multiple IP numbers). If the alternative is separate adapters and lines for three or more users, a router is actually a bargain.
There are two caveats, though. First, configuration procedures and documentation for routers tend to be aimed at network administrators rather than at ordinary mortals. If you're in the latter category, you should arrange to have your administrator or Internet provider talk you through the setup process. Second, most routers do not have RJ-11 ports for connecting phones, fax machines, or analog modems to your ISDN line. If you hope to replace your standard lines and do all your telephony over ISDN, installing a terminal adapter may be a better bet. (This situation may be changing: The latest router from Ascend, the Pipeline 25x, provides two RJ-11 ports, and some other vendors are expected to follow suit before too long.)
Question 7: What Else Should I Know?
ISDN Is Surprisingly Doable Now -- but only if you plan ahead. We've heard quite a few horror stories from folks who have jumped onto the ISDN bandwagon without doing all their homework. After investing significant sums of money and time, many of them simply gave up. To prevent this, be sure to figure out what services and hardware you need and how much they'll cost you. Make sure your telephone company can support your chosen hardware. Above all, plan to spend time troubleshooting your connection. Armed with realistic expectations, solid information, and a well-designed plan, you should be able to get ISDN up and running in your home or office.
Henry Norr is editor emeritus of MacWEEK.
Hardware Checklist / Tips for Buying Gear
DON'T EXPECT TO SHOP FOR ISDN equipment the way you do for most Mac products. You won't find it on the shelves at a dealer's or even in the pages of a mail-order catalog. Your best bet is to check with your phone company's ISDN marketing group, with ISDN-savvy Internet service providers in your area, or with local consultants and value-added resellers. These sources often offer hardware at a healthy discount if you sign up for their services.
In any case, it doesn't pay to select your hardware in isolation. Because ISDN is a complex technology offering a variety of implementation options, you can't take interoperability for granted. In fact, many ISDN service providers and corporate IS departments maintain a list of compatible products, and they may refuse to support any product not on the list. Still, at some point, you will need to choose among products. Here are five questions to ask:
* Is an NT-1 built in? Every ISDN line requires a device
called a network terminator, or NT-1, as an interface between
the line and local equipment. Some TAs and routers have an
NT-1 built in; others don't. When considering a device that
doesn't, be sure to factor in the cost of adding an external
NT-1 -- about $200.
* Does the device have one or more RJ-11 connectors? Most
TAs and cards have at least one RJ-11 connector, but most
routers have none. If you want to use your ISDN line for
voice calls, faxing, and modem connections to non-ISDN sites,
you will need these connectors for your analog equipment,
unless you buy an external NT-1 with connectors of its own.
(Another option: Both IBM and Motorola make terminal adapters
that have conventional modem capabilities built in; if you
get one, you won't need a connector for your old modem.)
* Is the device able to combine the two B channels of an
ISDN BRI interface? This enables you to turn the two channels
into one large pipe for large file transfers, a process known
variously as multilinking, inverse multiplexing, or bonding.
The importance of multilinking is sometimes exaggerated;
after all, 64 or even 56 kbps is ample bandwidth for most
purposes. Besides, doubling your bandwidth may cost extra,
since phone companies and Internet providers treat each
channel separately; for their purposes, you're using two
minutes of service for every minute you have both channels
open. Still, it's nice to have multilinking available if you
need to download a huge file in a hurry.
* Does the device support MPP? Until recently, most ISDN
devices did not offer multilinking. Other devices implemented
proprietary bonding technology, so whether they worked
depended on the equipment installed at the other end of the
line. Earlier this year, however, an Internet task force
hammered out a new standard, multilink PPP, that should
ensure interoperability. It's still in testing at this
writing, but look for it in new devices.
* Does the device have flash-ROM firmware? Flash ROM makes
it possible to upgrade your unit with new software -- a much
cheaper and more convenient approach than replacing ROM
chips. Some developers, however, support updating only from
PCs. Make sure that the developer provides a utility that can
update the ROM from Mac software on disk or via an online
service.
Resources / Getting More Info
IT'S BOUND TO HAPPEN -- you'll have questions galore and you'll need more information. Where to go next? Here are the best sources we've found:
* Dan Kegel's ISDN page. This site
(http://www.alumni.caltech.edu/~dank/isdn) consists of a
well-organized collection of links to hundreds of sites
providing information about ISDN technology, products, and
services.
* The Usenet newsgroup for ISDN. Members of the group, at
comp.dcom.isdn, maintain a multipart FAQ (frequently asked
questions) file on ISDN.
* CompuServe. To reach CompuServe's ISDN forum, type GO
ISDN.
* Bellcore, the telephone industry's central research
organization. Although your local phone company's
customer-service representatives may be clueless about ISDN,
Bellcore supports both a Web page
(http://www.bellcore.com/ISDN/ISDN.html) and a toll-free
national ISDN hot line (800-992-4736) with detailed
information about ISDN availability around the country.
* Your regional Bell operating company. Most of the Bell
operating companies also have 800 numbers for ISDN
information: Ameritech (800-832-63282), Bell Atlantic outside
NJ (800-570-4736), Bell South (800-428-4736), NYNEX
(800-438-4736), Pac Bell (800-995-0346 or 800-472-4736), and
Southwestern Bell (800-792-4736).
* Intel. Call 800-538-3373, and ask for extension 208. Intel
has lots of good, free information on ISDN equipment,
