7-D Automatic telephone system in the Haarlem rural area

The Haarlem rural zone forms part of the project to convert the Dutch telephone system into automatic working and is one of 19 into which the country is divided. Each zone embraces a number of centre exchanges grouped round a main exchange. Junctions radiate to the centre exchanges from the main exchanges, the centre exchanges forming pivotal points of the sectors. Full automatic operation is provided throughout the zone. All traffic from a centre is routed via the central exchange. Toll traffic is dealt with on a manual basis and is concentrated in the main exchange. A consistent numbering scheme is used for all rural zones throughout the country. The prefix K ( = 0) is allotted, followed by three digits. The first digit indicates the zone, the second the sector in the zone, and the third the desired exchange. The prefix is omitted for local calls and only the numerical designation dialled. The paper traces by aid of a trunking diagram the routing of the various types of calls. Photographs of exchange equipment accompany the paper.