"Key Telephone System with automatic switch"
(The large picture changes on "mouse over" the number of the phone or the circuit diagram).

Picture
System overview: Schema
1925 Catalog number: 5873 5874 5881 5882 5883 5884 5885 5886 5887
Circuit number: AS-242 AS-242 AS-244 AS-244 AS-243 AS-245 AS-243
1925 Catalog number: 5888 5889
Circuit number: AS-245 AS-245
1928 Catalog number: 5881 5882 5883 5884
Circuit number: AS-242/4 AS-242/4 AS-242/4 AS-242/4

System overview: Schema
1932 Catalog number: 7854/55 7854-57
Circuit number: