Switchboards BD-96 is a complete, transportable, single-posi tion telephone switchboard serving magneto lines and trunks. Trunk circuits are provided for connection to common battery lines of either manual or automatic central offices. Drop signals are associated with the lines and trunks for indicating incoming calls, and with each cord circuit for supervisory signals. The BD-96 has a capacity of 40 lines, 4 trunks, and 12 cord circuits. The BD-96 is the switchboard of the TC-4.