T4 Vs. T3 Line Internet Access

By Jim Farthing

When trying to make the decision between a T3 line and a T4 line, the main considerations are how much bandwidth you need and how much money you have to spend on the line. The second question may be easy to answer, but the first one can be much more difficult.

Available Connections

When people talk about connections, you will hear T1, T3 and T4 as well as DS-1, DS-4 and others. T1 and DS-1 are about the same thing. There may be some minor technical differences, but the terms can be used interchangeably.

T3 and T4 lines require fiber-optics, whereas a T1 line is carried over normal copper lines. This makes T3 and T4 lines easier to install since it is easier to install one fiber-optic line than three or four copper lines.

Line Types

A T1 line is equivalent to 24 phone lines. A T1 can handle 1.5 million bits per second. It is important to note that it is "bits" per second and not "bytes" per second. In computer terms, a byte is 8 bits. So a line that is capable of carrying 1,500,000 bits per second can carry 187,500 bytes per second. T1 lines are typically used by small businesses for their networks for serving Web pages from their own servers.

T3 Line Specifications

A T3 line can carry 44.736 million bits per second. A T3 is the equivalent of 28 T1 lines. T3 lines are the most common for large businesses that need a lot of dedicated bandwidth for their networks exclusively or for Internet connectivity to their servers.

T3 lines are still widely used by many medium-sized businesses, as are T1 lines. The T3 and T1 are the most widely used.

T4 Line Specifications

A T4 line can carry the equivalent of six T3 lines. A T4 can carry 274.176 million bits per second. This type of line is used only by major corporations. As of 2009, Sprint uses T4 lines for its Internet backbone. The Internet backbone is a network that crosses the United States several times as well as around the world and carries all of the Internet traffic.


There are a lot of considerations that must be taken into account when trying to decide which type of line is needed for a business. The business should determine if it needs only network connectivity or Internet access. These dedicated lines can be quite expensive, so the business must budget for the costs.