The 203-type telephone was a desk set hand telephone for use on two-party telephone lines for tip-party ID message rate service. It was an anti-sidetone telephone identical in purpose to the 151C desk stand (http://www.classicrotaryphones.com/forum/index.php?topic=12354.0), but used either a B6 (round base) or a D6 (oval base) handset mounting. As such it was the anti-sidetone upgrade to the 103-type telephone.
The 203 typically used either a 634-BC or 684-BC subscriber set with a six-conductor mounting cord. The circuit is essentially identical to its 151C/684-BC cousin. However, due to the different form factor, the hookswitch is divided into two assemblies operated simultaneously by the handset cradle plunger.
The circuit shown here is drawn according to the wiring diagram shown in Western Electric's No. 9 catalog (1935). It is based on the D6 mounting with a 4H dial.
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