10 forgotten wonders of 1980s homes

On 30 December 2015 at 01:34, Chuck Guzis <cclist at sydex.com> wrote: #4/#4A crossbar is *not* a local switch. It's a four-wire toll switch. The only local crossbars were #1 (the replacement for panel), #5 (the one that really embraced the common control ideas), and #3 (about as close to a CDO as you can get with crossbar). Sounds like you had a #1 crossbar then, if only because #5 wouldn't dial pulse unless you had to deal with a step tandem (or were calling into a step office). The direct successor to the 4/4AXB was the 4ESS/4AESS. (Meanwhile the successor to the local crossbar offices was 1ESS/1AESS; save for the weird 3XB which was replaced by the small 3ESS.) And of course both local and toll ESS have been replaced by the 5ESS. Fun Facts about toll crossbars: There were three crossbars for toll switching. The Crossbar Tandem (based on #1XB technology), the Number 4/4A Crossbar (four wire dedicated toll switch), and the Number 5 Crossbar. One can setup a 5XB to do double duty as a tanem switch; in fact in the 1975 and 1977 Traffic Routing Guides you can see several places where this is the case (for example Moncton, New Brunswick). Interconnects between different networks: About as fun as IBM versus DEC. Cheers, Christian -- Christian M. Gauger-Cosgrove STCKON08DS0 Contact information available upon request.