T1 Lines Vs. T3 lines

T1 and T3 lines are both dedicated telecommunications lines that run on reserved circuits through fiber optic or copper cables. These lines are leased, usually by businesses, from telecommunications companies, and they are considered superior to cable and DSL high-speed Internet services. However, T1 lines and T3 lines have a few differences that should be considered before entering into a contractual lease.

Overview of T1 and T3 Lines

T1 lines were first developed by Bell Labs in the 1960s as an efficient system for transmitting digitized voice communications. After T1 lines were developed, T2 and T3 lines were created by using a multiplex of T1 lines, which means that T3 line rates are higher than T1 rates but provide more bandwidth.

What makes T1 and T3 lines special is that they are dedicated lines between single subscribers and the telecommunications company. They are not shared like standard telephone lines are. Another distinguishing feature of T1 and T3 lines is that they are purely digital, so analog voice or data signals must be converted before transmission.

T1 and T3 lines are considered the backbones of business communications systems for both voice and data. Some of the types of organizations that employ them include the following:

  • Government agencies
  • Schools
  • Customer service centers
  • Hospitals
  • Hotels
  • Financial institutions
  • Manufacturers


Standard telephone lines are analog lines capable of carrying 64 Kbps of information, which is enough for a single voice transmission or the transmission of information through a 56 Kbps modem. By comparison, digital T1 lines are capable of transmitting up to 24 voice calls simultaneously, which is enough for offices with 24 to 100 employees to make phone calls without a delay. One of the 24 lines in a T1 connection is often dedicated to caller ID, which reduces the available lines to 23.

The total bandwidth that can be handled by a T1 line is 1.544 Mbps. This bandwidth can be split between voice calls and data transmission, but when bandwidth is dedicated to Internet data, the number of voice lines is reduced.

T3 lines are multiplexes of 28 T1 lines that work in conjunction to provide much higher bandwidth. The 44.736 Mbps of T3 bandwidth is the equivalent of 672 standard phone lines. However, T3 rates are usually about eight to 10 times those of T1 rates, which provides for a great discount when high bandwidth is required.


T1 rates are much more affordable than T3 line rates, but the tradeoff is less bandwidth. Both T1 and T3 lines are leased, and nearly all telecommunications companies charge a monthly fee to subscribers of either of them. T1 rates in the United States average between $500 and $1,500 per month, and T3 rates are usually between $5,000 and $15,000 per month. Specific rates often depend on the distance from the subscriber’s location to the nearest telecommunications hub. Quotes for T1 and T3 lines can be provided by reliable online agents by filling out a simple request form or by giving them a call.


T1 lines are scalable through fractional T1 service, but because T3 lines are little more than bundled T1 lines, it makes more sense to downgrade to a T1 instead of scaling down fractionally.

Fractional T1 lines usually start at 128 Kbps, and they are very affordable. These fractional lines are perfect for small businesses, startups or individuals with high bandwidth needs, and whenever more bandwidth is required, it can be added up to the maximum of 1.544 Mbps. If bandwidth greater than 1.544 Mbps is needed, then it is a simple matter to scale upward to a T3 line.

A T3 line is top of the line in standard practice. T2, T4 and T5 lines exist and can provide more scaling possibilities, but these aggregate lines are rarely used in practice. Even the largest corporate networks are adequately served by T3 lines