DSN100 DEFENSE SWITCHED NETWORK ADJUNCT comcode: 407 559 285 pec code: 8804-025
INDEX Overview of the DSN network Characteristics of the network Terms used with the DSN Network Programming the DSN100 Call management Answering an incoming precedence call Placing an outgoing precedence call Drawings Tie trunk translations Specifications

Overview of the DSN network

The DSN (Defense Switched Network), a part of the Defense Communications System, is a military network that provides preemption capabilities for calls related to national defense.
The DSN interface, when added to a PBX (Private Branch Exchange), allows attendants and other users of the system to enter the military network by dialing an access code. Users can get assistance on outgoing DSN calls by dialing an attendant-assistance code.
Calls on the DSN network may be precedence or non-precedence calls. Precedence calls are routed over trunks called precedence capable trunks. These calls can be routed through the network without attendant assistance.

Characteristics of the network

DSN Network has the following characteristics that distinguish it from other types of networks:

• A numbering plan that defines 7 digit dialing for DSN calls inside a system and 7 or more digits for DSN calls outside a system.
• DSN calls carry with them one of five precedence levels:
  1. Routine
  2. Priority
  3. Immediate
  4. Flash
  5. Flash Override

Calls of one precedence level may be preempted automatically or manually when a call of a higher precedence level is attempting completion.
Incoming precedence calls to an extension that does not answer in a specified period of time (from 10 to 60 seconds) are routed to an extension available 24 hours a day. The extension must then attempt to complete the call.

• Terms used with the DSN Network

  The following terms are used in this guide and/or other DSN documentation; they should be familiar to all DSN users.

  • Preemption - the disconnecting of an established call and re-seizing of the same line or trunk by a call of a higher precedence level when no idle circuit is available to complete the higher precedence call.
  • Precedence - a rank assigned to indicate the degree of preference to be given in processing and protecting DSN calls; originators of precedence calls may elect to use their highest authority level or any lesser precedence level.
  • Flash Override (FO) - the highest precedence level for DSN calls.
  • Flash (FL) - the second highest ranking precedence level for DSN calls.
  • Immediate (IM) - the third highest ranking precedence level for DSN calls.
  • Priority (PR) - the fourth highest ranking level for DSN calls.
  • Routine (RT) - the lowest ranking precedence level for DSN calls.
  • Dial Service Assistance (DSA) operator - an operator associated with DSN switching center who provides services such as information, interception, random conferencing, and precedence calling assistance to PBX attendants on DSN calls.