Editing Autovon (section)

==Numbering plan==
AUTOVON used a numbering scheme similar to the [[North American Numbering Plan]]. The network had its own three-digit area codes for various geographic regions around the world. Each area code covered several three-digit exchange codes, usually corresponding to the central office telephone switches serving each installation. Thus, almost any telephone on a military base could be direct-dialed via AUTOVON. A selected set of telephones were [[Four-wire circuit|four-wire]] AUTOVON phones, wired directly into the AUTOVON network. Others could initiate AUTOVON calls with operator assistance.

Though the [[telephone numbering plan|numbering plan]] was similar to the U.S. civilian scheme, the routing structure was a very complex ''polygrid'' system unlike the civilian [[Telephone exchange|office classification]] scheme, which used a 5-level hierarchical system in which longer-distance traffic, in general, was handled by higher-level switches.  It was barely within the information processing capabilities of the Number Five Crossbar switching system which implemented it.  The non-hierarchical routing structure was intended to get around any number of nodes destroyed in war.  This system inspired similarly survivable ones for message networks, including in future decades the [[Internet]].

Local base switches would be connected to a few AUTOVON trunks, which the user would access by dialing 8 (or in some cases, 88) before the telephone number. To dial locally a user would dial 9, and to dial using commercial long-distance, 1 (where this was supported). The [[United States Department of Defense]] (DoD) charged access to AUTOVON according to a complex billing system, and each base budgeted according to local practice.