With the shift to a new generation of telephone technology from electromechanical switching to electronics and computer control, a new generation of phones was needed that could take advantage of the services offered by the new technology. One prerequisite was that the new phones should have a keypad, instead of the traditional dial. The first Ericsson keypad phone was named the Diavox.
In the spring of 1969, Ericsson and Televerket, Swedish PTT, decided to work together on developing a new telephone. A working group was appointed, and extensive preparations were made that included a survey of development trends in 13 countries and a study of the Swedish market. Interviews were conducted with experts at Ericsson, Televerket and Ellemtel. Studies in other countries largely confirmed the results obtained from studies in Sweden. The working group recommended that Ellemtel should be given the assignment to develop a telephone for the future. The goal was that it should be possible to launch the phone in 1978.
The requirements for the new phone included that it should have a separate receiver and be equipped with a keypad for either tone or pulse dialing. It should also be possible to equip it with a dial. The microphone was to have an extended frequency range and provide better speech quality than previous models. It was also desirable to be able to use the telephone as a starting point for special models.
Because design is extremely important for telephones, four industrial designers were contracted to design the new phone. A total of ten different design proposals were submitted, which were eventually reduced to two. The final choice was a design produced by Breger & Co. in Stockholm.
The Diavox contained much more electronics than previous phones. Instead of a dial, it had a keypad. Pulse dialing was used when the telephone was connected to conventional telephone stations. When key were depressed, pulses were generated electronically that corresponded to those produced by a dial. Keypads for tone dialing, on the other hand, transmitted two tones for each key press. These were used on telephones that were connected to electronic, computer-controlled telephone stations. This allowed access to a number of new services, such as automatic callback on busy, automatic wakeup calls and short numbers. An "R" (Recall) key was introduced to allow new services to be accessed from tone dial phones. A small number of Diavox phones were produced with dials for testing, but they never became standard phones.
Speech quality was improved by replacing the carbon microphone with an electronic speech circuit. Automatic receiver regulation had been introduced with the Dialog phone, but the Diavox included transmission regulation that adapted the phone to the subscriber line's characteristics. This was perceived as an improvement by callers.
L M Ericsson produced the first Diavox phones in 1977 and 1978. The first shipment went to Saudi Arabia for use in a new telephone network being built with AXE technology. In 1981, the Diavox was produced as a wall phone in white, green, red and beige colors. The Diavox was also the starting point for more advanced models including a multi-line phone and a speakerphone.
Subsequently, the Diavox was produced by both Ericsson and Televerket. A total of just over four million phone, of which about three million were tone dial phones, were produced for Televerket. Production was discontinued in 1989.
Author: K V Tahvanainen