1. Telephone switching network

Today, the worldwide telephone network interconnects 600 million main lines. It is, to date, the largest machine designed by man.

Every network has meshes and nodes. The same applies to the telephone network, where the meshes are the transmission lines and the nodes are the switching centers. The transmission function is easy enough to understand. Switching, on the other hand, is a rather complex concept.

Thanks to telephone switching and the principles defined and standardized from the outset by the ITU (International Telecommunication Union) and one of its committees, the CCITT (Comité Consultatif International Téléphonique et Télégraphique), the world's networks are completely interconnected. It is therefore possible, where the equipment exists, to link two users very quickly from any point in the world. As a result, there are many different...