The image on the right does not show a Dutch Telephone set, because it is an English BPO Telephone no. 232, built on top of an additional box. This CB Phone was connected to the non automatic Switch Board of the Brittisch Telelecom Dealing Room. The additional wooden box holds the LB-circuit, for the connection to a Leased Line. So, seen in historical perspective, it was the first ARBITRAGE Telephone.

DUTCH TELEPHONES FOR THE PTT SWITCHED TELEPHONE NETWORK

The automation of the Dutch Public Telephone network started about the year 1925. Now people were able to make there own connection by using a Rotary Dial. The manual ringing generator and the microphone battery, of the existing LB-telephones, were not useful anymore, because the new (CB)telephone set was fed out of the Telephone Exchange. The integration went not as flexible as wanted, because it took some time before the automatic exchanges were installed everywhere. In most of the villages and smaller cities the local manual exchanges had to be updated to accept the new CB- telephones. At first you were manually connected to a 'City Line' of the Automatic Exchange in the city. After that you could use your own dial.

Because the first Automatic Exchanges in the Netherlands were manufactured by Siemens & Halske in Germany and Ericsson in Sweden, it was obvious to use Siemens or Ericsson telephones. The big cities like Amsterdam, Rotterdam and Den Haag had there own Private telephone network and also there own favourite suppliers. The Dutch state network has chosen for Siemens, because of the best adaptation to the new Exchanges and network. The first CB-model was the W28 (desk and wall-type with black metal dial) telephone from Siemens and a special version (with nickel Dial) was manufactured for the Dutch market in 1929. In the year 1931 the Dutch manufacturer HEEMAF began to produce telephones under the Siemens W28 license. Our neighbour countries also began to produce telephones under the Siemens license, so it was the most copied telephone of that time and with a few differences they were all W28 'look a likes'. The HEEMAF telephones were made of Bakelite parts with a steel plate cask. In 1938, the nickel dial was replaced by a Bakelite version and the microphones 'Dome', by a little horn. Another major change was made in 1951. The telephones internal circuit was adapted to the Dutch underground cable network according to the new National PTT standard, Norm 51. This was a great improvement on the quality of the speech and the Speech Intelligibility as well. The circuit also allowed an easy connection of many peripheral apparatus. On the HEEMAF telephones, for a few years, the HEEMAF logo was replaced with the text NORM 51 in the same shape as the former logo.

Because the Norm 51 was a well researched standard, for many years is was used in newer T65 telephones and lasted to the Eighties. The last Norm 51 based telephones were the Ericsson type DIAVOX and the ITT/NSEM type UNIFOON.