T1 High Speed
Dial up internet is of the past, but luckily with new technology, T1 connections allow people to connect with speed and ease. The growth in the interconnection of personal computers, terminals and telephones in the business environment has been increasing exponentially. T1 technology is proving to be a cost-effective means of linking voice and data, both inter-office and intra-office, and serves as an alternative to high speed modems.
Additionally, it is good to know that after a byte of data is sent from each channel there is an extra bit used for synchronizing called a Frame bit. 193 bits are sent and this increase of 1 bit per 192 causes the speed to increase to 1.544 Mbps. There is significant discussion these days about "T1 Gateways" and "T1 trunks" as the cost from the various phone companies of these services goes down. Users are discovering that it costs less to have a T1 trunk than a series of leased telephone lines in a point-to-point topology. This increase in the use of T1 requires a fundamental understanding of the technology.
It is good to know that ACCUNET T1.5 is a two-point, dedicated, high capacity, digital service provided on terrestrial digital facilities capable of transmitting 1.544 Mb/s. The interface to the customer can be either a T1 carrier or a higher order multiplexed facility such as those used to provide access from the radio.
Luckily, a convenient way to think of T1 is from the International Standards Organization and Open System Interconnect model: the Physical and Logical layers. The Physical layer focuses on the electrical characteristics such as signal shape, voltage levels, etc. The logical layer deals primarily with the format issue.
Keep in mind that T1 is a high speed digital network developed by AT&T in 1957. T1 was put into use in the early sixties to support long-haul pulse-code modulation voice transmission. The primary innovation of T1 was to introduce digitized voice and to create a network fully capable of digitally representing what was once an entirely analog system.
In the definition of T1, there is a hierarchy of services. Each tier of the hierarchy is designated by a speed in Mbps. There is T1 which is simply a network with a speed of 1.544 Mbps and was designed for voice circuits or "channels. In addition, there is T1-C which operates at 3.152 Mbps. There is also T-2, operating at 6.312 Mbps, which was implemented in the early 1970's to carry one Picturephone channel or 96 voice channels. There is T-3, operating at 44.736 Mbps and T-4, operating at 274.176 Mbps.
