 The A1 was only distributed for a very short time until the B-type telephone mount (model 102 telephone) was completed in 1927, a streamlined design that replaced the tube-shaft with a sculpted cone shape.By 1930 this round base was redesigned into the oval-footprint D-mounting to avoid instability of the unit when dialing.At the same time the electric circuitry was upgraded to produce the model 202 telephone, which reduced the strong sidetone characteristic of earlier designs.