NCJ Number
201518
Journal
Corrections Today Volume: 65 Issue: 4 Dated: July 2003 Pages: 70-72
Date Published
July 2003
Length
3 pages
Annotation
This article discusses the T-1 Primary Rate Interface, a communication system used by prisons to reduce costs.
Abstract
A T-1 is a digital transmission link that was developed by AT&T in 1957. It was implemented in the 1960's to support long distance pulse-code modulation voice transmission. The primary reason for this method was to use the limited number of copper telephone lines around the world while carrying the increasing number of telephone calls. In the T-1, all digitized sound is carried over two single wires commonly called a twisted pair. The Electronic Private Business Exchange (EPBX), also referred to as a switch, permits staff to call every extension in the facility and place calls to telephones outside it. Most of them have other features, including an “off hook” alarm that can be set off when officers or other staff may require some type of assistance. A trunk is a communication line between an institution’s EPBX and the larger exchange switch at the local telephone company that carries only one telephone call at a time. A T-1 will deliver 24 usable trunk lines over 1 single cable pair and many other options on an EPBX that can be delivered to each telephone equipped with readout capabilities. Many EPBX software applications will permit correctional facilities to manage these lines automatically and if a few POTS (plain old telephone system) lines are retained for safety reasons, the software will pick the line that costs the least to use, a process called least-cost routing. The advantages of a single T-1 include lower cost, total line usage 24 hours a day, and the ability to set up a number of telephone features. Depending on the State and telephone company, these features could include call waiting, three-way calling, conference calling, anonymous call rejection, and remote call forwarding. For large States that have 30 or more institutions, there could be annual savings of more than $360,000, which could be used for other more important security issues. 1 endnote