A military 4-wire field telephone incorporating an electronic signalling system

A new field telephone has been designed for use with the 4-wire electronic switchboards now being developed for the U.S. Army Signal Corps. This local battery instrument incorporates new features in systems applications. All telephone signalling to and from the switchboard is accomplished on a voice frequency basis, thereby providing compatibility with radio and wire carrier. The digit tone signalling plan is readily adaptable to the use of a key-type selector set. The latter affords more rapid digit setup speeds than are possible with the use of the conventional rotary dial. The introduction of a 4-page wire system eliminates critical hybriding in the telephone as well as throughout the switching centers.