Full maintenance of telephone and telegraph systems in occupied countries
is essential for German control. This raises many technical problems; for
example, in Europe telephone communication is often made through roundabout
connections; the hook-up between nearby rural subscribers is often put through
by means of connecting-junctions terminating at distribution centers, often a
distant town.
In case of breakdown, whether due to sabotage or other causes, the Germans
decided that machine switching systems were too complicated to permit
quick resumption of operations. In some cases, they provided against this by
installing manual boards, suitable for connection to the main frames of a telephone
distributing center. This permitted them to reestablish an immediate restricted
service.
In occupied European territory, the Germans have employed 4-wire
rubber-covered cables with encased loading coils inserted in the cables by means
of coupling joints. Thus, two physical circuits and a phantom circuit were obtained
from each cable. The cables were strung on convenient objects, such as
branches of trees, or laid on the ground, sometimes in groups of perhaps 20. The outer
diameter of the cable was about 3/8 in., and that of the loading coil
container, about 2 in. At elevated points, short lengths of cable comprising
loading coil assemblies were looped and suspended to relieve strain.