1 Telecommunication networks and digital subscriber lines
1.3 Metallic access network

The access telecommunications network are based on symmetrical copper pairs in most European countries. Conception design of the network counted mainly with the provision of telephone services via analogue phone lines POTS (Plain Old Telephone Service) in the frequency range from 300 Hz to 3400 Hz (ie. classical telephone channel) or basic digital connections BRA-ISDN (Basic Rate Access - Integrated Services Digital Network) in the range up to 80 kHz.

The access networks of largest telecommunications providers in the Czech Republic are based on metallic cables whose basic element is a spiral quad and symmetrical pair.

Cables using wires with copper cores with diameters of 0.4, 0.6 and 0.8 mm diameter insulation max. 1.7 mm and have an outer casing predominantly of polyethylene. Cables in the bearing are filled with a suitable embodiment the filling material (gel), which forms protection against water. Conductors have polyethylene foam isolation. Cables in the self-supporting version (hanging cables) are not filled and full use polyethylene isolation. Part of the access network in the Czech Republic but also uses historical copper cables with copper conductors with diameters of 0.4, 0.6 and 0.8 mm with an air-paper isolation.

Access networks other telecommunications operators are, in comparison to the largest network providers, relatively small and covering a small geographic area. For this reason, throughout this module we discuss parameters and operating conditions of the network elements in the access network only the largest providers.