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From: MJK2660@RITVM.BITNET (Mike Koziol)
Newsgroups: comp.dcom.telecom
Subject: AT&T Phone Model 7405
Message-ID: <8711030220.AA01095@ucbvax.Berkeley.EDU>
Date: Sat, 31-Oct-87 22:36:01 EST
Article-I.D.: ucbvax.8711030220.AA01095
Posted: Sat Oct 31 22:36:01 1987
Date-Received: Fri, 6-Nov-87 21:48:23 EST
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Approved: telecom@xx.lcs.mit.edu

This past year we had an AT&T system 85 switch installed on campus and
an AT&T model 7405 (with display panel) telephone was installed in my
office. I was told at the outside that the phone was capable of many
options, and to never unplug it as it may not work when I plugged it in
again. Since I'm basically a curious sort a friend and my self recently
disassembled it and found two rather large circuit boards populated
nicely with lots of chips and a couple of EPROMS. I have a few questions:
what "processing" does this phone do, what is stored in memory, how
volatile is the memory, what is the phone capable of, and finally why
shouldn't I unplug it? Any ideas?