The Slimtel was designed and built by BT. It was not a great success. It was by far from being the first one-piece telephone but many before it were much more compact. The dumpy shape was required to cover two separate printed circuit boards and a complex mechanical switch hook with an ‘easy-dial’ button – an early form of ‘hands free’ dialling, though there was no loudspeaker monitor. It came with a wall bracket. It had several ergonomic problems. The keypad was too small for many adult fingers and its electronic ringer had a most unpleasant loud trilling sound. Over time, the plastic number label cover fell off.
In 1985 it was relaunched as the Slimtel 10 (see third image), with the easy dial and secrecy buttons dumped in favour of a 10 number memory, but it was still a ‘turkey’.