47 C.F.R. § 211.5
There are hereby established four levels of restoration priority. Within each level, subpriorities may be established by the Executive Agent, with the concurrence of the National Security Council, for both government and nongovernment services. The subpriorities categories currently in use, which have been established by the Executive Agent will remain in effect until modified. Compatibility of subcategories applicable to government and nongovernment users is essential to achieve the objective of a single restoration priority system.
(a) Priority 1. Priority 1 shall be the highest level of restoration priority, and shall be afforded only to Federal and Foreign Government private line services, and to Industrial/Commercial services which are designated for prearranged voluntary participation with the Federal Government in a national emergency. Circuit requirements in this level of priority shall be limited to those esential to national survival if nuclear attack occurs for:
(b) Priority 2. Priority 2 shall be the second highest level of restoration priority, and shall be afforded only to Federal and Foreign Government private line services, and to Industrial/Commercial services which are designated for prearranged voluntary participation with the Federal Government in a national emergency. Circuit requirements in this level shall be limited to those essential, at a time when nuclear attack threatens, to maintain an optimum defense posture and to give civil alert to the U.S. population. These are circuit requirements whose unavailability would present serious dangers:
(c) Priority 3. Priority 3 shall be the third highest level of restoration priority and shall be afforded to government, quais-government, and Industrial/Commercial private line services: Provided, however, That Priority 3 will be afforded circuits serving Industrial/Commercial, State, county, municipal, and quasi-state and local government agencies only where, during an emergency, at least one station in the circuit (or in connected circuits if switched service is involved) will be manned continually, or where such circuits are automated and will be under constant surveillance from a remote location. Circuit requirements in this level shall be limited to those necessary for U.S. military defense and diplomacy, for law and order, and for national health and safety in a national emergency involving heightened possibility of hostilities. These are curcuit requirements needed to: