DSN is the Defense Switched Network, which is, among other things, the DOD worldwide telephone system. DSN telephone numbers can only be dialed from one DSN telephone number to another telephone on the Defense Switched Network. Civilian phone systems can not send or receive calls to or from a DSN phone.
When dialing a DSN telephone number from CONUS to CONUS, the 312 is not required and should not be dialed. When dialing into the following geographic areas using the DSN system, the following area code prefixes must be used:
317 (Alaska) 312 (Canada) 313 (Caribbean)
312 (CONUS) 314 (Europe) 315 (Pacific)
318 (Southwest Asia)
The phone number listings on this website contains defense telephone numbers and prefixes whenever available. All telephone number formats listed assume that the call is being placed from CONUS for DSN. For example, the DSN telephone information for Ramstein Air Base in Germany looks like this: Main installation number: DSN-314-480-1110. All telephone information sections for Germany and for most installations in other countries with DSN dialing capabilities follow this same basic pattern.
The DSN area codes are not used when dialing from the same area code, e.g., the DSN area code of 314 (Europe) is not used when dialing to a DSN number in area code 314 (Europe) from another telephone with an area code of 314 (Europe).
NOTE: For more detailed information on the DSN telephone network, and a global directory of DSN phone numbers, please visit the following website: http://www.disa.mil/Network-Services/Voice/SBU-Voice/Directory.