AT&T® ISDN Direct Service
AT&T® ISDN Direct Service gives you a low-cost way to transmit high-speed data and high-quality voice over a single telephone line simultaneously. ISDN Direct offers data transmission at 64 kilobits per second (Kbps) over a non-dedicated line, compared to a standard phone line and modem providing 28.8 Kbps. And ISDN Direct lets you use the same line for packet-switched data traffic.
ISDN Direct lets you buy what you need and pay for what you use. How? ISDN Direct monthly charges are largely usage based. This means fewer lines for the same amount of traffic—without the cost of coaxial or fiber-optic wiring. Depending on you usage, ISDN can cost less than flat-rate digital private lines.
What about capacity? ISDN Direct lets you combine a single line's two 64-Kbps channels, giving you a 128-Kbps pipe. Such capacity gives you a low-cost way to carry video conferencing, connect users to LANs, and inter-connect LANs. For long distances, ISDN Direct Service provides 64-Kbps clear-channel end-to-end transmission. So you can have worldwide connectivity as provided by interstate or international carriers.
ISDN Direct Service also taps the full call-processing power of AT&T's network—giving you access to Caller ID and all the features of a sophisticated, premises-based key telephone system, at no additional cost.
You get...
Bandwidth on Demand—For occasional use of applications like video conferencing, ISDN Direct lets you easily aggregate bandwidth whenever needed—giving you private-line performance without the expense.
Instant Response—ISDN Direct Service provides nearly instant response for traffic like on-line database look-ups. This means fast, inexpensive data access.
Combined Resources—ISDN Direct lets you interconnect isolated or dispersed LANs, linking then to form a single, powerful resource for your organization.
Inexpensive Backup—ISDN Direct provides an economical backup to your existing private lines.
Home Office—ISDN Direct gives you the only inexpensive way to move your staff's LAN-based desktops to their homes.
Compatibility—ISDN Direct conforms to international standards, so you can easily get the equipment needed for your applications.
It's good for...
LAN interconnection
On-line database access
Desktop video conferencing
Private line backup for disaster recovery
Telecommuting
Credit card verification
Distance learning
Team engineering and design
High-speed file transfers
How It Works
In AT&T's Network
Each ISDN Direct single-line connection is made up of two circuit-switched voice/data B channels operating at 64 Kbps and one packet-switched data D channel operating at 16 Kbps. AT&T's circuit-switched network carries digitized voice, data, or images from the B channels, while their packet-switched network carries signaling data from the D channel.
At Your Premises
Each ISDN line connects to your premises at an ISDN network termination unit (known as an NT-1). Analog phones and non-ISDN terminal equipment must connect to a terminal adapter or ISDN terminal equipment in front of the NT-1. ISDN phones and ISDN adapter card-equipped terminals can connect directly to the NT-1. You can connect up to eight services per line.