When the 706 telephone was first introduced in 1959 it was known as the Modern Telephone. It was made in two versions, the Mk. I version was conventionally wired, whilst the Mk. II version used a printed circuit board. The Mk. I had a plastic base on which all the components are mounted and the interconnections made by conventional wiring. Mk. II and IIA had a metal base on which a printed wiring board is mounted with most of the components soldered directly on to it. All electrical components other than the gravity switch, spring sets and bell mechanisms are identical in each version. Each instrument is supplied with an extensible coiled hand-set cord which extends from 200mm to about 1524mm. Line cords were available in lengths of 3.00m, 5.0m and 8.0m. The telephone handset weighs 255g and the complete instrument weighs approximately 1.6kg. The 706 was available in seven standard colours: black, light ivory, concord blue, lacquer red, topaz yellow, two-tone green and two-tone grey.

The original 746 design, shown on the left, was released in 1967, however the recess for the handset to sit on the top of the phone was too broad. This enabled either the handset to be carelessly placed or to slip out of position off the switch hooks, which took the telephone off-hook. As can be seen from the picture on the right, in around 1971, the top of the 746 case was redesigned with a narrower recess to prevent the handset from sliding off the switch hooks.