What is Transmission System 1 or T-1?

T-1 is the North American digital standard for high capacity transmission of telephony and data communications. In data communications, T-1 links are used to directly connect CPE (Customer Premises Equipment) routers to the Internet and for Private Data Network or VPN circuits. A full T-1 service is usually sold as a complete circuit and is often referred to as a digital trunk line. A T-1 is a dedicated circuit from the telecommunications provider to the customer and is not shared with any other customers. This is why it is often referred to as a dedicated line. The full circuit can be either data or voice, but not both.

A T-1 circuit is a dedicated digital data carrier transmitted over copper wiring and is used to carry voice and data at speeds up to 1.5 million bits per second (1.5Mpbs). T-1's are most commonly installed as dedicated links between two office locations or from a customer to the internet.