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Voice Telephone Calls (31X)

Voice telephone calls can access a DSN line by either direct dialing or dialing the operator. Here is how each process works.

If you do the dialing:

  • Listen for the dial tone.
  • Dial the DSN number access number if required.
  • Listen for the DSN dial tone
  • Dial the desired DSN phone number, with precedence and area code if required.

If the operator dials for you:

  • Give your name and local base telephone extension number.
  • Give your precedence.
  • Provide the DSN number you are calling and any other information.
  • Wait on the line until the operator connects you to the called party.

Data Telephone Calls (50X and 51X)

Transmission of data on the DSN will be allowed by exception and will be severely limited by Combatant Commanders, Services, and Defense agencies. The NIPRNet and SIPRNet are the primary networks for data transmissions.

Dial-up Data

Use of DSN switched voice (dial-up) circuits to transmit digital data will not be detrimental to voice users. Long circuit holding times will affect the network grade of service (GOS) and significantly degrade other users' ability to complete calls. Data processing equipment may use DSN voice circuits only when the DDN and other transmission media, either commercial- or government- owned, do not exist or are required for emergencies or reasons of national security. Data equipment includes computer-controlled graphics (other than facsimile), word processors, mainframe and microcomputers, laptops, and other personal communications system (PCS) and similar equipment.

• Data processing equipment using DSN voice circuits (dial-up) will use a STU-III or be capable of automatically disconnecting from the access line or interswitch trunk when the transmission is complete or the circuit is preempted.

• Approval authority, for outside CONUS (OCONUS) data transmissions through DSN dial-up circuits, is the Combatant Commander. CONUS authority is the Combatant Commander, Chief of the Service, or the Director of the Defense Agency concerned. Each request will be coordinated with DISA to determine the network impact. DISA will be notified of each approval specifically to determine why the DDN cannot support the requirement. Blanket approvals for use will identify a connect limit, and expiration or revalidation date.

Dial-up Facsimile. The DSN may be used to transmit unsecured facsimile traffic without a STU-III only if the facsimile machine or computer transmits within one minute after the facsimile transmission ends or the circuit is preempted.

Secure Transmission with a STU-III/STE

Use of a STU-III or STE in the secure mode for voice communications is not interpreted as data transmission. When the STU-III/STE is used to transmit secure data or a facsimile, the following criteria will be met:

  • The STU-III/STE at each end will be monitored during the entire transmission to ensure the circuit is maintained and the STU-III is in the secure mode.
  • The STU-III/STE preempt feature will be enabled at all times.
  • National guidance for the use of STU-III/STE in secure data transmission, including access control, TEMPEST, and computer security, must be followed.

    When the STU-III reaches End-of-Life, it will no longer be supported.

Conference Calls

To schedule a conference call across the DSN, contact your local operator. Tell the operator that you wish to make a conference call and provide the operator with a list of numbers to be included in the conference. Preset conferences may be established. Consult your supporting DISA Field Office for further information.

Calls to Commercial Numbers

Official long-distance calls may be placed using a combination of DSN and local base switchboard lines. When authorized by the local commander's policy, base switchboard operators may connect incoming DSN calls to a local commercial number if the called commercial number is within the toll-free radius of the switchboard. Off-net operations are at the day-by-day discretion of local base officials. Due to the possibility of abuse and difficulty of control, the automatic completion of on-off-net calls is not authorized. Though DSN off-net capability exists at many military installations, DISA does not provide off-net directory service for official calls.

Inter-Area Calling

The DSN provides global telephone service for authorized users. Some users can call everywhere while others are limited to one particular area or combination of areas. Where you can call depends on your mission and how your telephone line is class marked. If your calling area is limited, you will not be able to dial outside your calling area. The local directory indicates the calling areas and codes available to you.

The area code need not be dialed for calls within your area. Calls to an area outside the local call boundary require an area code plus the 7-digit DSN number. If you are transmitting data, alternate area codes are used.