T1-class leased lines can be used to connect organizations to the Internet or create a private intranet. If you lease T1-class services between your business locations, you have total control and guaranteed privacy. There are many twists on T1-class digital services. Those who require more or less bandwidth can lease multiples or fractions of a T1 line, depending on their needs. T2 provides 6.3 Mbps, and T3 goes to 44.7 Mbps.
Fractional services offer lesser but still guaranteed bandwidth.
Burstable services guarantee a certain fraction of a T1 connection but can reach higher peaks. And many ISPs resell copper or fiber cable T1 connections provided by local carriers, marrying capacity with the content and other services ISPs provide. Note, however, that you can sometimes get a better rate negotiating the ISP and circuit from separate services. Ordering and installing the connection are the trickiest part of any T x relationship. The circuit contract typically does not include the router or other equipment needed to integrate the circuit with a local network.