From: Bill Stewart <stewarts@ix.netcom.com>
Date: Sun, 5 Nov 1995 08:07:19 +0800
To: cypherpunks@toad.com
Subject: Re: Telephone switch capacity
Message-ID: <199511042351.PAA07347@ix4.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


>	Please be aware that the current capacity of the
>telephone system in the United States (and for that matter,
>most of the developed world) is only capable of supporting
>between 15 and 20 percent simultaneous telephone
>conversations.  If the FBI wishes to set up a system that is
>capable of monitoring 1% of the total number of lines, that
>equates to a ability to tap 5%, not 1% of all calls in progress.

The FBI now says they only want to tap 1% of simultaneous capacity,
not 1% of total number of lines.  On the other hand, the actual utilization
of the telephone network is also much lower than the number of lines -
back when I was a voice-telephony geek, our estimates for busy-hour
phone utilization were about 1/12 for residential and 1/6 for business
(3 and 6 hundred call-seconds per hour); that was before widespread
use of fax machines, modems, or LANs, so business utilization has
probably increased.  Equipped trunk capacity was typically enough to
have a maximum of 1% blocking during busy hour, which means a certain
amount of margin over average calls in progress, and switch capacity 
depends radically on technology - some kinds of switches are non-blocking,
while others have various capacity limits.

"One Bell System - It Works!"
#---
#                                       Thanks;  Bill
# Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com
# Phone +1-510-247-0664 Pager/Voicemail 1-408-787-1281
#---