From: [email protected] (Scott Fender) Subject: Re: ESS & DMS Question In a previous posting, Lee Hardiman ([email protected]) writes: > In article <[email protected]>, [email protected] says... > I'm not a phreaker or anything but I keep hearing these two acronyms > (ESS & DMS) and I'd appreciate a little info on what the difference is > between the two and how it affects the phone your using. Thanx. > > ESS stands for Electronic Switching System and is a term used to refer to > switches manufactured by AT&T. DMS is a trademark of Northern Telecom. > Both refer to switches that use a computer to control the switch matrix. > A DMS, #5ESS, nad #4ESS are digital switches. A #1ESS uses an analog > switch matrix. > Also to complete, it "DMS" simply stands for "Digital Multiplex Switch". Common DMS versions are: DMS-10 -serves areas a bit outside the main city centres. It links small communities to a larger DMS-100 located in a larger city. DMS-100 -This is the local exchange. Used all over Canada except in rare cases where No. 5 X-Bar is in use, and in even more rare cases where SxS is still running. It is programmed in BNR proprietary Pascal, in PROTEL, and in Assembler (rarely these days). It is upgraded by software loads that take place every six months, with *major* software changes taking place every 18 months. The loads take place at 3 AM local time. These BCS loads (Batch Change Supplements) can be quite take longer than expected sometimes, and weird things can happen. Because of this the switch is always "mirrored" prior to any new load and can revert back to its former state if the trouble persists. To simplify the load process, the loads are now done via PCL's, which are smaller and take advantage of more modular software currently written. Each PCL is specific for each individual switch operating in North America. DMS-200 -This is a local operating company toll switch. DMS-250 -This switch local/toll used by the inter exchange carriers MCI, Sprint etc. DMS-300 -This is a ISC switch and can do all the conversion between the International circuit (CCITT System No. 5) and various North American systems like R1 (Regional System No. 1), SS6, and SS7. Both AT&T's switches and NT's (BNR designed) DMS switches are quite advanced. They can "get" you if they want to. Take it easy guys, Scott. ([email protected]) P.S. Hope to see you all at Cafe Wim (Ottawa) this Friday.