From AllBusiness.com*

A T1 line for high-speed Internet access isn’t the answer for every business, but depending on your needs it could be your best option. These frequently asked questions and answers will explain what a T1 line is and help you decide whether or not you should purchase it for your business.

What is a T1 line?
A T1 line is a high-speed digital telephone line that transfers signals at 1.544Mbps and accommodates up to 24 telephone lines or trunks. A T1 line can be used in place of separate local trunks and lines from the local telephone company. It also has the ability to bypass your local telephone company and connect directly to your long distance service provider.

Should I consider T1?
Initial costs for T1 equipment and installation are quite high. However it may be might be a cost-effective option if you:

• Need at least 10 to 15 voice-grade channels that connect to your local or long distance service provider
• Host Web or FTP sites on your network
• Require high-capacity data bandwidth (256Kbps to 1.544Mbps)

Can I bundle other services with T1?
Common bundles offered with T1 service include combinations of local phone service, long distance service and Internet access. Most service providers offer discounts on cost-per-minute rates for long distance if you use their T1 line for voice and data.