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 MIL-HDBK-232A
5.3.4 Telephone networks and instruments. There are various types and
configurations of secure telephone networks and instruments in use within the
DoD. Due to this variety, it is difficult to develop a standard procedure
which would apply to all elements of the secure voice community.
5.3.4.1 Secure telephone switches. Secure telephone switches such as
AUTOSEVOCOM are used to provide switching capability for secure voice
terminals and to provide interface capability between various types of
equipment. Physical security precautions should be commensurate with those
for other REAs and adequate for the level of classification of calls
processed by the switch. As a minimum, the area should be designed as an
REA. When a secure voice switch is collocated with secure or nonsecure data
systems, it is recommended that the switch be installed in an area which is
remoted from the other system(s). All signal and control lines should
utilize cable which uses an overall nonferrous shield with the shield
circumferentially grounded at both ends. All wire lines, to include signal,
control, and power, should be installed in ferrous-type conduit. This is
necessary to provide maximum protection, and to isolate RED/BLACK line.3 and
digital and analog systems. An equipotential ground plane should be used for
all grounds except the ground FPSS, which should be connected to the ground
bus of the servicing power panel. Separate grounds should be run for all
pieces of equipment with the conductors being continuously run, i.e., not
spliced. RED and BLACK equipment should be separated in accordance with
table I.
5.3.4.2 RED voice systems. A RED voice system is an unencrypted voice
network with physical protection and distribution such that it may be used
for classified communications. RED voice systems may be used within an LEA
as an internal secure telephone network within a RED enclave. When this type
of system exists, all cables should have a nonferrous overall shield. All
cables, to include signal, control, and power, should be installed in ferrous
conduit. No unencrypted telephone lines should penetrate the LEA barrier.
Lines which must connect to other secure telephone systems or the dial
central office should be connected to a secure voice switch or other
encryption device prior to the point of egress of the LEA.
5.3.4.3 Secure voice terminals. Approved secure voice terminals, such as a
TSEC/KY-3, may be installed in or external to LEAS. When installed in an
LEA, where other communications equipment is used, all cables should be
installed in ferrous conduit. The terminal should be separated from other
electronic devices in accordance with table I. Only those telephone
instruments and cables designed for the specific system should be used. If
the telephone instrument is remoted from the terminal, the interconnecting
cable should be installed in ferrous conduit. Terminals that are installed
external to an LEA should be installed a minimum of 6 feet (1.8 m) from other
electronic equipment. Conduit for wire lines is not required if other
electronic devices are not used in the same general area. Grounding may be
provided by structural steel.
5.4 Signal distribution. The objective of signal distribution is to take a
signal from one point to another in such a manner that the signal is not
interfered with, does not cause interference, and is not misrouted. The
designer and installer must consider:
a.
What type of signal is being distributed.
b.
What type of cable best supports that signal.
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