The public telephone networks

Telephone networks are known as public telephone networks.

They consist of :

•  Trunk exchange .
•  Local exchange .
•  And lines between them .

The lines can be divided into trunk lines and local lines.

Simplified Trunk Cable Diagram

1- The Trunk Networks

Lines which are used for trunk traffic only are described as trunk lines . These networks can be designed as :

•  Meshed networks
•  Star networks
•  Or mixed networks
• Transmission medium
•  Symmetric copper pair
•  Coaxial copper cable
•  Optical fiber
•  Air (radio )

Trunk /network Configuration