Before we continue, the differences between the commercial numbering system and the tactical
numbering system should be identified. The commercial system uses a 10-digit plan, while the tactical
system uses a 7-digit number. We also need to remember that the terms used in the tactical and
commercial system differ.
Situation: You will develop a telephone directory for a non-MSE unit.
2. Development of the tactical telephone numbering system. The tactical telephone numbering plan is
based on Military Standard 188C. The plan considers the limited number of automatic switches in the
field. In addition, the standard considers the management, engineering, and planning involved in the
development of a tactical automatic switch network. The tactical telephone numbering system provides
the commanders the flexibility necessary to satisfy mission requirements. MIL-STD 188C provides
standardization across the network to include EAC.
a. The grid system. Using the grid system, PRs correspond to a specific geographic or grid area
assigned to theater, corps, and division. Each grid area will have assigned the necessary PRs required to
service the area without affecting the service. Within each grid, switch designators are normally used to
designate automatic switches, manual switchboards, and semiautomatic switchboards. The theater
communications system planning element (CSPE) makes the PR and SL assignments for each level of
b. PR assignment by grid. The first two digits of the seven-digit tactical telephone number
represents a PR or area within the theater of operations. Normally, a Theater Army or a corps will
probably only use one PR To simplify the planning, a grid system can be used to assign the PRs. The
theater commander, through the CSPE, will designate geographical PRs based on the war plans, unit's
mission, and terrain. The theater commander, through the CSPE, can also determine adjacent PRs
permitting the planning of communication systems before the advance of friendly forces.
c. Although we can use the grid system to assign our PRs in a theater of operations, this should not
restrict us in the number of PRs we assign to our system. The number of subscribers and the size of the
area should be our guide in determining how many PRs we will have. The advantage of assigning PRs
by grid is that a corps or division can retain the assigned PR for an indefinite period of time, establishing
an identity with a particular PR.
3. PR numbers. The tactical telephone numbering plan uses PR numbers the same way as the
commercial system uses area codes. The theater commander can designate PRs in a way that will allow
him to identify elements within his command. Some of the tactical PRs are listed in Appendix B.