Answer: trunklines

AnswerCrossword Clue
TRUNKLINES

Main phone circuits

TRUNKLINES

Communication channels

TRUNKLINES

Long-distance arteries

TRUNKLINES
Major long-distance channels
TRUNKLINES
Major phone connections
TRUNKLINESDirect telephone connections
TRUNKLINESPhone connections
TRUNKLINESMajor transportation routes
TRUNKLINESMain telephone connections