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Additional FAQs with or without suggested answers, should be sent via e-mail to the DSN webmaster for possible inclusion.

What is the DSN?
The DISN Network provides global voice services through the Defense Switched Network (DSN), a world-wide private-line telephone network. Multilevel precedence and preemption (MLPP) capabilities on the DSN utilized by command and control users ensure that the highest-priority calls achieve connection quickly, especially during a crisis situation. The DSN also provides global data and video services using dial-up switched 56 kbps or 64 kbps Integrated Services Digital Network (ISDN) services. Secure voice services are provided by the Secure Telephone Unit, Third-Generation/ Secure Terminal Equipment (STU-III/STE) family of equipment that provides end-to-end encryption over non-secure DSN circuits. Interfaces are provided between strategic and tactical forces, allied military networks and EMSS. The military services and agencies in the Department of Defense (DoD) are authorized users, but other federal government departments and agencies, allies and DoD contractors can also use the DSN if approved by the Joint Staff (in accordance with CJCSI 6215.01). For more information, go to DISA Direct, an e-business ordering and tracking system. Contact your telecommunications control officer to expand service at an existing location, or contact the DSN service manager for new service activation.

Who is listed in the DSN Directory?
Any post, camp, base, or station served by the DSN that formally requests to be included in the directory is listed. Individual listings are restricted to command level, agency level, or organization level. To be included in the DSN Directory, or to correct or delete an existing directory listing, complete the form included in Appendix A of the Directory (Request for Listing).

Requests can also be sent via e-mail.

Where can I obtain information if DSN services are already approved by the Joint Staff in accordance with Chairman of the Joint Chiefs of Staff Instruction (CJCSI) 6215.01? If it is not already approved by the Joint Staff, what are the approval procedures? Where can I locate other requirements that must be met for access to DSN?
One half of a floor in Crystal City and the leaser provides commercial service and our users require DSN in and out of the facility. Defense Telecommunications Service Washington (DTSW) said that we would need to purchase and install a separate switch, telephones and our own commercial trunk. To be able to use the leaser PBX and limit access to an office, please review the sites below.
APL Testing and Certification
Approved Products List (APL)
DOD Unified Capabilities (UC) - Schedule

The contractors in Balad, Iraq are currently setting up to call one of two numbers in the U.S. (504) 391-7900 and (703) 343-8999. Once they are connected, they then call the DSN lines on base. Who do I call to get them fixed, and who is the local responsible organization for these numbers?
The numbers you’re referring to, 504 and 703, are not DSN numbers in the US, and we are not responsible for commercial numbers. You'll probably need to contact Verizon or the base you are connected to, to find out who is providing the service.

Is it possible to have a DSN number outside of a government base?

Yes there is a way, but if you are a contractor you must have a sponsor and there are monthly recurring costs involved. Furthermore you will have to be connected to a certified switch.

Does one have to report on the NexCom switches in the BOQ/BEQs? The MCX connectors at our site have a central exchange (Centrex) installed. Do I have to report that?  Neither of these touches the DISN backbone, but they're here.
Yes, the Office of the Secretary of Defense (OSD) tasking letter states "...a complete inventory of all telecommunications switches that are, or will be installed or connected to the DSN (to include tactical switches) or public switched telecommunications networks" needs to be completed.

If we have three EOs on a base; a host switch and two Remote Switching Units (RSUs) how do we report them? 
Report them as three separate switches. Be sure you specifically state the function of each switch and report the host switch as your Remote Switch.

On one of the DSN Online forms there is a field for O&M Organization. Should I use my Office Symbol here?
No, whoever operates and maintains the switch is the real answer. For example, in Hawaii the answer is a DISA contractor. The agency is DISA. At most sites it will be the organization (for example: 198 Signal Battalion, NCTAMS-LANT NORFOLK VA/N2).

Can a DSN user dial a world-wide 1-800 number to receive assistance with a problem?
Yes, you can call our DISN Global Service Center (DGSC) at 800-554-3476 or DSN 850-4790.

How do I dial DSN from Lansing, Michigan to Bamberg, Germany?
We are not sure if you have a DSN switch board number. All the numbers we have worldwide can be found in the DSN Directory.

I work with a number of military customers but have no way to dial a DSN number. Is there a Web-based tool available which will convert DSN to commercial numbers?
The only way to dial a DSN number is to have a DSN line. A workaround would be if you can find a military base operator's commercial number and see if they will transfer your call. All of our commercial/DSN conversion numbers are listed in our DSN Directory.

Can I convert DSN 314 442 7110 to a commercial number?
For conversion assistance please contact DSN.

How do you call to a DSN phone number from an ordinary US home phone, and please, just a brief explanation? The following Using the DSN page gives complicated ones.
You cannot unless a base will transfer your call, and we do not know which ones will and which ones will not. Each base decides whether these specific call transfers are supported or not.

I am trying to find a number that I can dial on my DSN "fax machine" that will let me send faxes back to a 1-800 number in the U.S.
There is a DSN number 809-463-3376 that can only be used with calling cards or 800 numbers. Just dial the number like any other DSN number, wait for the second dial tone then follow the instructions on your calling card or dial the 800 number.

I was told that one can use a DSN phone from Iraq to call a switch near your homeport and then use a calling card so that it is not international rate, but local or national rate. Is this true and what is the entire number I would need to call if I was in Iraq trying to call Naval Base Ventura County Port Hueneme area? Where is the closest switch?
The DSN number 809-463-3376 is what you can use with a calling card. Dial the 809 number just like you would any other DSN number, wait for the second dial tone, then follow the instructions on your calling card or dial your 800 number. If a location/individual has an 800 number, then you wouldn't need a calling card, just dial the 809 number and wait for the dial tone, then dial your 800 number.

I had a DSN phone number that connected me directly to a dial tone, so that then all I had to do was enter my calling card number and I was connected. It by-passed the operator and went straight to the dial tone. 
The DSN number to use with a calling card or 800 number is 809-463-3376.

I have a relative overseas who asked me to search for a DSN number so that he may call to U.S. Would you be able to direct me to a DSN that would be acceptable for the Dallas-Ft. Worth, TX area?
There is a DSN # 809-463-3376 that can be used if the calling card or the number being dialed is an 800 number. You first dial the 809 number, wait for the second dial tone, then follow the instructions on the calling card. Some bases will transfer their calls to commercial numbers, but we do not know who they are. They can find in our DSN directory.

We have contractors in Southwest Asia who need to contact organizations who do not have DSN phone capability. Is there a number they could dial to give them access to DSN?
Unless they have the commercial number of a base that will transfer their call or have a DSN line put in, there is no way.

I am stationed in Madrid, Spain. Is it possible to call a DSN phone number from a commercial phone if the commercial equivalent is not listed or unavailable? We do not have DSN capability here, and often need to call DSN phone numbers. Is there a central operator who can transfer calls from a commercial network to the DSN one? If not, is there any way to get DSN here?
The only way to call from commercial to a DSN line is to find a base operator somewhere that will transfer your call. We have commercial and/or DSN-equivalent listings for some locations in the DSN Directory. You may try calling one of the base commercial numbers to see if they will transfer your call. Also, you may want to check with your NATO contacts because they do have DSN access in some locations. Furthermore, you may at least call them and they may transfer your call. Because the requirements for having access to DSN are very involved, we would recommend trying the above.

We received a new DSN prefix, 591. From time-to-time, we receive complaints that other bases cannot dial our new prefix. A deployed person in Honduras (DSN prefix 449) could not dial 591. The Commercial Squadron called their tech and the prefix was programmed into their switch. Is there anyway to ensure that bases have our new prefix programmed into their systems?
It is the responsibility of each location to notify their Community of Interest (COI) when they acquire a new number, and it is DISA's policy that the bases do not restrict their switches from calling a DSN prefix. Our DSN switches screen the prefixes for validity and provide recordings when not a valid number. We are unable to ascertain why 449 could not dial 591, unless the 449 number is being restricted for some reason. Do you know what happened when 449 tried calling 591? Knowing this might help us determine the cause.

I am currently stationed in Iraq and have been issued an IraqNet cell phone. I need to be able to call locations that have only DSN and VoIP phone lines and have been unable to do this. Personnel need to be able to reach me from a DSN line. 
We are not sure how you accomplish this using an IraqNet cell phone on DSN. We recommend that you contact whoever gave you the phone. The phone would have to be certified to use on DSN and I don't believe they are. Unless both of you have DSN, you won't be able to call each other and would have to call commercially.

Is it possible to acquire DSN services for our new VoIP system? We currently have DSN service but would like to get it directly from you for our VoIP system.
At the present time we are not offering VoIP over the DSN backbone. There are some bases switches that have it, but they can't get from the base to our DSN. We are working toward this capability and hopefully, in the near future, this will be a service we can offer.

What are the various rates for standard voice calls using DSN? What are the "per minute" charges for voice calls based on the distance covered by the call?
DSN no longer charges minutes of use since DISN Subscription Services (DSS) (formerly EPP) was established. There are approximately 400 customer DSS/EPP sites that subscribe to DISN Transmission, which includes various subscription services of which DSN voice services is one of the DISN products/services included in the yearly cost of the pipe. So, if you are a customer on a base that is an EPP/DSS site and the predominant DISN services user is paying for the pipe subscription, the customer can call DSN all he wants and not be charged for minutes of use. The service included in-cost of yearly subscription of transmission.

Any service that we currently use is provided by the Navy in their NSWC Crain, IN facilities. We are located about a mile outside the gate in a new technology park. We are the first building in the park and we are trying to move some of our contractors to free up the government space. Could you give me details for the cost, connection and switch? I assume our particular NSWC Crane customer would be the sponsor.
A government sponsor and the purchase of a certified switch from our APL, is required. The government sponsor will need to write a letter of justification to the Joint Staff, copying this office, stating why the DSN service is required.  Please don’t forget to make clear whether global access is required, how many people will be using the service, whether two-way/one-way is used, and if there is a specific custom/location that calls will be made to.

When an organization moves, we will be in need of phone service to include DSN? How do we request guidance/assistance on obtaining such service?
Please get in touch our DISA Scott office at DSN 770-8710 or 8674 or commercial (618) 220-8710 or 8674. You'll need to go through a certified switch; if not your own, then maybe you could be connected through another switch close by that is already connected to DSN.
Accreditation Accreditation is the formal approval to operate which is granted by the Designated Approval Authority (DAA)
APL Approved Products List
ATO Authority to Connect
BEQ Bachelor Enlisted Quarters
BOQ Bachelor Officers' Quarters
C2 Command and Control
CENTAF US Air Forces, US Central Command
CENTCOM US Central Command
Centrex Central exchange
Certification Certification is the evaluation of the technical and non technical security features of an information system. Certification is granted by the Certifying Authority.
CJCSI Chairman of the Joint Chiefs of Staff Instruction
CO Central Office
COI Community of Interest
Comm Communication
COMSEC Communications Security
CONUS Continental United States
DAA Designated Approval Authority
DFAS Defense Finance and Accounting Service
DISA Defense Information Systems Agency
DISN Defense Information System Network
DIACAP DoD Information Technology Security Certification and Accreditation Process
DoD Department of Defense
DoDI DoD Instruction
DSN Defense Switched Network
DSS DISN Subscription Services
DTSW Defense Telecommunications Service Washington
EO End Office
EMSS Enhanced Mobile Satellite Service
FAQs Frequently Asked Questions
FIPS Federal Information Processing Standard
FMP Follow-Me Paging
FSO Field Security Office
GBS Global Broadcast Service
GNS Global Notification Service
GSCR Generic Switch Certification Requirements
Hz hertz
IA Information Assurance
IAO Information Assurance Officer
IASE Information Assurance Support Environment
IIS Internet Information Server
INA-T Iridium North American
IO Interoperability
Interoperability Certification The DISA test facility at JITC has certified several telephone switch models as interoperable. JITC has posted the list of certified switches on their Web site. If you cannot determine the status of your telephone switch certification, put NO on the inventory.
ISU Iridium Satellite Unit
ISDN Integrated Services Digital Network
IWRS Improved Weather Reconnaissance System
JITC Joint Interoperability Test Command
kbps kilobits per second
MCEB Military Communications-Electronics Board
MDA Message Delivery Area
MLPP Multilevel Precedence and Preemption
NATO North Atlantic Treaty Organization
NCR National Capital Region
NIPRNet Unclassified but Sensitive Internet Protocol Router Network
NMCB Naval Mobile Construction Battalion
NSTISSP National Security Telecommunications and Information Systems Security Policy
NSWC Naval Surface Warfare Center
O&M Operations and Maintenance
OCRS Online Compliance Reporting System
OSD Office of the Secretary of Defense
PBX Private Branch Exchange
PDI Potential Discrepancy Item
PIN Personal Identification Number
PM Program Manager
PSTN Public Switched Telephone Network
RSU Remote Switching Unit
SERS Special Emergency Radio Service
SIM Subscriber Identity Module
SIM Card Also known as a "smart card," A SIM card is the physical item that contains all necessary information for uniquely identifying a subscriber.
Software Patch Levels Vendors send out bundled software load updates (software code) known as patches, to update and/or fix problems in the software. The software load and software patches are considered when a switch is certified by DISA. You may require the software vendor to provide you information on the software patch levels.
ST&E Security Test & Evaluation
STIG Security Implementation Guide
SRR Security Readiness Review
SSAA System Security Authorization Agreement
STU-III/STE Secure Telephone Unit, Third-Generation/Secure Terminal Equipment