ISDN

SNET Internet no longer offers ISDN access services. This information is intended for existing ISDN customers.

Introduction to ISDN

What is ISDN?
How does ISDN work?
What do I need to use ISDN?
What are the ISDN access numbers?

ISDN and the Internet

What is ISDN Internet?
What do I need to use ISDN Internet?

Specific Technical Questions

Will I receive a full 128 Kbps connection?
What are the minimum system requirements?
Can I switch speeds dynamically?
Do I need the Microsoft Accelerator Pack?

Glossary

SPID, NT-1, power supply, terminal adapter

More Information

isdnaccess@snet.net (e-mail us!)
ISDN, by Intel
ISDN, by Dan Kegel

Introduction to ISDN

What is ISDN?

Imagine a fast, switched digital network for data, voice, and video. Now, imagine the same network running on the same wires used by the existing worldwide telephone network.

You have just imagined the Integrated Services Digital Network, or ISDN.

You can think of ISDN as a faster, digital connection--for speaking, for faxing, for sending and receiving video, and for reaching the Internet (as discussed in the next section, ISDN and the Internet).

ISDN offers many benefits, including:

• Speed. ISDN can send and receive information at 128 kilobits per second (Kbps), or four times faster than a 28.8 Kbps modem. With data compression, the effective speed may reach 512 Kbps.
• Simultaneous connections. ISDN allows two types of communication to occur simultaneously. For example, you can talk on the telephone and download information from the Internet at the same time. One ISDN line eliminates the need for two separate phone lines.
• Fewer errors. ISDN provides clearer voice and virtually error-free digital data communication.
• Enhanced calling features. With ISDN, you can tell whether an incoming call contains data, voice, or video. ISDN also supports caller ID, call management, and call record keeping.
• New communication potential. ISDN allows you to communicate in ways that were previously impractical. Some of the new applications enabled by ISDN include: high-speed Internet access, fast file transfer, remote network access, video teleconferencing, dual-line usage, and advanced telephone features.

How does ISDN Work?

The most common type of ISDN--the Basic Rate Interface (BRI), which is ideal for individuals and small business users--consists of three data channels: two bearer (B) channels and one data (D) channel. Each B channel carries 64 kilobits of information per second (Kbps). This high speed is ideal for two-way voice, data, fax, and video communications. The two B channels operate independently of one another--you can simultaneously send a fax on one B channel and talk on the second. The D channel operates at 16 Kbps and commonly supports the two B channels (for example, it initiates and terminates the B channels' connections).

What do I need to use ISDN?

To use ISDN you will need an ISDN line, an RJ45S data jack, an NT-1 device, a power supply, and an ISDN terminal adapter (or a router, a bridge, or other connecting device). The specific equipment you will need varies depending on the types of communication services you plan to use.

What are the ISDN access numbers?

Stamford: 203-817-7638
Hartford: 860-372-7638
Danbury: 203-8267638
New Haven: 203-815-7638
Deep River: 860-374-7638
Cornwall: 860-419-7638
Torrington: 860-387-7638
Waterbury: 203-819-7638
Norwich: 860-373-7638
Putnam: 860-382-7638
Bridgeport: 203-814-7638
Norwalk: 203-818-7638
Southington: 860-414-7638

ISDN and the Internet

What is ISDN Internet?

When you connect to the Internet using ISDN, you will send and receive information at 64 Kbps (per channel). By combining the two B channels in your ISDN line, you can communicate 128 Kbps, or four times faster than a 28.8 Kbps modem. (With data compression, even higher speeds are possible--up to 512 Kbps.) All this speed means you will spend less time waiting, more time downloading or surfing.

If you use one B channel (that is, a 64 Kbps connection) for your Internet connection, you will still have one channel free for talking on the phone or sending and receiving faxes.

What do I need to use ISDN Internet?

To connect to SNET Internet via ISDN, you need one of the following terminal adapters (all of which have been tested and work with the SNET Internet service):

Adapter	Mac	Win 3.x	Win 95/NT
Adtran Express XRT	No	Yes	Yes
3Com Impact	Yes	Yes	Yes
USR Courier I-Modem	Yes	Yes	Yes
USR Sportster ISDN	No	Yes	Yes

You cannot use your analog modem to connect to SNET Internet via ISDN.

SNET Internet does not support ISDN routers at this time.

Specific Technical Questions

Will I receive a full 128 Kbps connection?

SNET Internet provides a 128 Kbps connection via ISDN. The limiting factor on the speed of your connection will likely be your computer equipment. External terminal adapters generally connect at speeds up to 115.2 Kbps, due to the restrictions imposed by the standard PC 16550 UART-based serial port. (Older PC's may be limited even further by 8250 UART ports.) Please consult the material that came with your PC for more information about your computer's port speeds.

If you install an internal terminal adapter, you do not have to worry about the speeds of your computer's ports. Unless you are comfortable opening your PC, you may wish to have the installation performed by a qualified technician. In most cases, an external terminal adapter suits most people's needs.

Macintosh users may encounter similar serial port limitations. Power Macintosh computers with GeoPort technology will be able to connect at a full 128 Kbps. Power Macintoshes without GeoPort technology will be able to connect at speeds up to 115.2 Kpbs. Other Macintosh models may be limited to 57.6 Kbps. Please consult the material that came with your Macintosh for more information about its serial port speeds.

What are the minimum system requirements?

The minimum system requirements for connecting to SNET Internet via ISDN are the same as the current SNET Internet system requirements. The manufacturer of your terminal adapter may provide further requirements.

Can I switch speeds dynamically?

If your terminal adapter supports dynamic bandwidth allocation, you will be able to dynamically switch between 64 Kbps and 128 Kbps when you need the extra speed during a connection. Please see the material that came with your terminal adapter for more information about dynamic bandwidth allocation.

Do I need the Microsoft Accelerator Pack?

Windows 95 users using an internal terminal adapter may wish to install the Microsoft Accelerator Pack (usually included with your terminal adapter). Please refer to the material that came with your terminal adapter--generally, the manufacturer will recommend the Accelerator Pack if it is necessary.

Windows 3.1 and Windows NT users do not need to install the Microsoft Accelerator Pack.

Glossary

SPID: SNET assigns you one or more SPID's (Service Profile Identifier), which identifies your location so a call's data packets can be routed to you. You need to set up your ISDN equipment to use the SPID's SNET assigns you after you order your ISDN line (please see the material that came with your ISDN equipment for help). An ISDN SPID has the format: area code, ISDN phone number, 0101. For example, a typical SPID looks like: 20365512340101.

NT-1: The NT-1 (Network Terminal 1) connects ISDN equipment to the ISDN line. In most cases, the NT-1 is integrated into the ISDN equipment. Please see the material that came with your equipment for more information.

power supply: Unlike traditional telephone lines, which carry their own power, ISDN lines need an external power supply. In some cases, the power supply is integrated into your ISDN equipment. Please see the material that came with your equipment for more information.

terminal adapter: A terminal adapter (TA) allows your non-ISDN equipment (like a computer, fax, or telephone) to use your ISDN line. There are many TA's available; for a list of TA's tested with the SNET Internet service, please see What do I need to use ISDN Internet, above.