AT&T Co’s Network Systems unit last week introduced what it claims is the first set of building blocks for creating wideband packet network to combine speech, data and image transmission over 1.544Mbps T-1 lines while meeting international standards. Aimed at telephone companies wanting to offer customers a bandwidth-on-demand ISDN facilities and to use their lines more efficiently and cost-effectively, the Integrated Access & Cross Connect System uses speech compression algorithms claimed to increase dramatically the capacity and flexibility of telephone company networks. AT&T reckons that Integrated Access & Cross Connect is the only product of its kind based on the Link Access Protocol – D, LAP-D, a CCITT standard for sending information over the D channel of the Integrated Services Digital Networks, and AT&T suggests that LAP-D compatibility is important because more and more ISDN information will travel over telephone company networks in the future. The reason for going to packet technology is that end users’ needs for transmission capacity can vary greatly from minute to minute, based on the information they are sending, and packet technology will make it easy for telephone companies to give their customers the transmission capacity they need as they need it, says AT&T, adding that it also makes it easy for phone company networks to adjust to sudden periods of network congestion. Describing as the first of what will be a new generation of bandwidth-on-demand products, obviating the need to give each customer a dedicated a transmission line that’s as big as a customer’s maximum need. Integrated Access & Cross-Connect instead swaps transmission capacity back and forth among dozens of channels. Moreover the company claims that it uses bandwidth so efficiently that it can lead to as much as a 400% increase in the capacity of telephone company facilities. As for the instantaneous voice compression technology from Bell Laboratories, AT&T claims it is so good that there can be five-to-one compression without any noticeable degradation in quality – that means a 24-channel system handling up to 120 speech channels. The Integrated Access & Cross-Connect system can be used to multiplex and cross-connect up to 24 T1 lines, and includes new network management features to make it easy to control: an AT&T 3B2-600 Unix computer is used as the Integrated Access Controller, giving network managers central control with support for up to 32 terminals, with access to standard operations systems. Alternate routing is a standard feature of the system for quick reconfiguration of high capacity networks. Worldwide in 1990 The Integrated Access and Cross-Connect System is available now in the US and will be available to international markets in 1990. Also on the Integrated Services Digital Network front, AT&T Microelectronics has released the 2B1Q chip set that it claims is the first to meet the American National Standards Institute, ANSI, U interface ISDN standard for transmission over standard telephone lines. AT&T claims that the new chip will prompt development of ISDN equipment that meets the U standard; sample quantities are $95, with production quantities available in the fourth quarter of 1989. The U interface standard, which refers to transmission over two copper wires, is part of the basic rate interface, the ISDN standard that governs how desktop terminals and telephones can be connected to an ISDN switch. And AT&T Microelectronics and Intel Corp have announced the first results of their joint development on local area networks and ISDN, with the availability of the T7220 twisted pair medium attachment unit, TPMAU, transceiver. The companies say the unit allows companies to add users to local area networks by using standard telephone lines – unshielded twisted pair wiring – rather than coaxial cable. Design samples of the T7220 are available now, with production scheduled for the second half of the year: they are priced at $15 each in quantities of 10,000-up.
