Read Frequently Asked ISDN Questions here: 
USTINET - ISDN FAQs


ISDN
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Converting an existing phone line to ISDN (Integrated Services Digital Network) offers up to two phone numbers on the same wire. Effectively providing two phone lines in one. It let's you send and receive data at up to 128kbps without compression, and 512kbps compressed. It's an affordable alternative to DSL or dedicated leased lines, costing considerably less and is available in most urban and suburban areas in the US and Canada. 


Why would you want ISDN?
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An ISDN connection to the Internet is fast. It provides for 128,000 bps bi-directional bandwidth, almost 4 times more bandwidth than a 33,600 bps modem and over twice as fast as 56K modems.

Ping times, latency and packet loss is also greatly reduced, meaning faster and better connections! 

     ISDN Ping Times: 
     64 or 128 kbps transmit and receive
     7,100 or 14,200 cps 
     Ping times as low as 45ms.
     Typical ping times are 60-80ms.

     56K modems Ping Times: 
      56 kbps receive, 33.6 kbps transmit
     6,200 cps receive, 3,700 cps transmit
     Ping times usually greater than 115ms.
     Typical ping times are greater than 150ms.

For Internet browsing, this results in loading a web page in 1/4 the time. For on-line entertainment, packet loss and lag cease to be an issue.

If you need an additional phone number but do not want to install any more wiring, ISDN may be the right choice. Plus, ISDN connections are digital, resulting in superb voice clarity.

ISDN also offers simultaneous voice and data communications. While browsing the Internet at 128 kbps using both bearer 'B' channels, you can receive or make a telephone call. One of the B channels will dynamically allocate itself for voice leaving the other B channel open for browsing the Internet at 64 kbps.


What do you need?
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For data or simultaneous voice and data, an ISDN adapter and either a 64k or 128k ISDN account package (from us, USTINET) and a PC running Microsoft® Windows® 95, 98, NT, 2000, Linux, Unix or Macintosh.

For two voice telephone numbers, you will require ISDN dual-line telephone equipment.

You will have to choose to convert your existing phone line into an ISDN line or have another line installed by your local telephone company. The Switchover from Analog to ISDN service is usually completed within 1 week, if your property does not require rewiring. Please consult your local telephone service provider for details on ISDN in your area.


What do we recommend?
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For data and simultaneous voice and data communications, The U.S. Robotics® Sportster® ISDN 128K MODEL 1 internal adapter is highly recommended. This is available at local computer stores, through online computer shopping sites, or from 3Com / US Robotics directly.

There are two versions of this adapter. The MODEL 1 has an integrated NT-1 and U-interface while the MODEL 2 has an S/T interface. This is indicated on the product package.


ISDN Technical:
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The Integrated Services Digital Network (ISDN) requires special switch equipment at the telephone switch. Only two wires (same as a regular analog telephone line) are required. A two wire ISDN line is also referred to as an ISDN Basic Rate Interface (BRI) line. ISDN lines require special telephones or a special device to connect a regular analog telephone for voice communication called a Network Termination unit -1 (NT-1).

The NT-1 converts the two wire ISDN BRI line, also called the U Bus, into the signals needed by the digital ISDN adapter (typically 6 or 8 wires) and voice telephone. The 8 wire connection after the NT-1 conversion is called the S/T Bus.

An ISDN BRI line with the NT-1 equipment integrates three logical digital channels into two wires. These 'logical' digital channels are termed the D channel and two bearer 'B' channels called B1 and B2. Typically, the B1 channel provides for Circuit Switched Voice and Data (CSV/D), the B2 provides for data only. The D channel provides 16kps and is used for setting up calls and the use of the B channels. Each B channel carries 64kbps for carrying digital data or voice signals.

At USTINET, a 64k ISDN account will connect the B2 line for voice calls as needed. This means that you can transfer data at 64k AND use the voice telephone at the same time.

There are two typical configurations of an ISDN BRI line (note: a D channel is always required). The first is one B channel which will provide for either voice or 64kps data bandwidth. The second is BOTH B channels which will provide for either 128kbps data bandwidth or 64kps data bandwidth with simultaneous voice.



Read Frequently Asked ISDN Questions here: USTINET - ISDN FAQs