T1 lines or links are traditionally made up of aggregates of standard telephone lines to make a bundled trunk. A T1 consists of 24 digital telephone links each handling 64Kbps and by utilizing multiplexing techniques the T1 trunk can then handle 24 x 64Kbps or 1.544 Mbps. This is achieved by sampling each of the 24 links in turn at a rate of 8000 times per second and giving each link in turn a chance to communicate. By doing this the entire 24 links can then be aggregated over the T1 link without any loss of quality. T1 trunks were first introduced for aggregation of local telephone line within the local loop, by bundling and transporting their individual traffic over a trunk was more efficient and required far less copper lines. Nowadays however, T1 links are also used to describe any data link with a capacity of 1.544Mbps.
T1 links can be channelized, 24 separate channels, or as a single data channel of 1.54 Mbps. T1 links are today often leased by companies to connect to remote offices to provide a mixture of telephone and high speed data services, such as Internet. T1 lines can cost up to $1,000 per month so they are typically out-with the budgets of small businesses. Fractional T1, which is sold in as little as 128kbpc segments can make T1 more affordable but ADSL has better and more affordable bandwidth per dollar. The big advantage of T1 over ADSL and its variants is that T1 is private it is not shared bandwidth. With ADSL, the advertised potential bandwidth may seem far higher than T1, but with T1, there are no contention rates whereby you share the bandwidth with up to 50 other users in a consumer package and maybe 10 in a business ADSL plan. With T1, you have all the capacity and privacy to yourself.
T1 links or leased lines can also be cost effective even for small businesses that have ten or more phone lines, instead of paying monthly-leased fees per line, the business can consolidate all the fees into one T1 service and payment. Virtual telephone services and hosted IP/PBXs can also benefit from using a dedicated T1 link either for maintaining 24 channels for telephony or for a dedicated data link to the cloud based hosted provider.