What is a leased line?

A Leased Line, also known as a ‘private circuit’ or ‘T1 leased line’, is a permanent dedicated communication link between two points. The link is separate from the public telephone network and is reserved exclusively for the leased line purchaser. Where a company's Internet usage is intensive, a leased line provides a far more cost-effective connectivity solution than more traditional ones such as ISDN.

A leased line can be a twisted pair, coax or fibre optic cable and may involve all sorts of other hardware such as coils, transformers, amplifiers and regenerators. Leased lines have varying data transfer rates the highest being a T1 line, which provides a maximum speed of 1.544Mbps. These transfer rates can be divided between voice and data signals using multiplexing techniques. If the leased line is being used to carry voice data then the line can also be connected to a phone system.

Large companies generally use leased lines to connect several geographically different networks within their organisation.Typical examples of this service are the BT Kilostream, BT Kilostream N, BT Megastream and BT LES Lan Extension Services available in 10MB, 100MB and 1000MB speeds with ethernet presentation ideal for offices within a short distance of each other.

The lease line is also widely used to connect offices to the web via a point of presence (POP), which is a fast connection directly to the Internet. A T1 leased line can connect over hundreds of users to the Internet effortlessly as long they are just browsing, a problem would only occur if they were to all start downloading files like MP3s. This service is known as Leased Line Internet Access with the most common being the BTnet Start and BTnet Flex leased Line internet Access Services.