14 



BELL SYSTEM TECHNICAL JOURNAL 



Fig. 7 — Private branch exchange switchboard arranged for 15 trunks and 200 stations. 



Fig. 8 — Private branch exchange— 1600 stations, 148 lines to Central Office, 151 

 tie trunks to other private branch exchanges, 42 switchboard positions, 60 operators 

 and 24 hour service. 



