While the 200 type telephone could be mounted on its bellset and some variants were produced for private systems with integral bells, the GPO looked to Ericsson of Sweden when it decided to introduce a one piece telephone. The 300 type telephone was originally designed by Ericsson’s Norwegian associate company in 1931. It was re-engineered for UK use to incorporate the 200 type handset and to add the same slide-out tray found on many 200s. It was first released in 1936 as Tele 332. See image below for a photo of the original Ericsson design. Differences in the Ericsson design compared to the 300 type include: Ericsson handset, Ericsson dial, side cord entry, plain, not plaited, cord, front number label and no slide-out tray.

Most were produced in black bakelite, and an advance on the 200 type was that the body was a single mould. Ivory, Red and Green were also available, again produced originally in urea formaldehyde. The 300 type telephone remained in production until the late 1950s, in particular the 312s shown above were produced in significant numbers to meet the demand for shared service lines, forced on the GPO by treasury restrictions on the purchase of copper cables.