Most telephone calls pass over the public switched telephone network or PSTN. Public means that access to the network is open to anyone willing to pay the prescribed charges. Switched means that the network has call routing equipment which enables a caller to reach any required destination on the PSTN. Some national PSTNs are owned by the government, others privately. Calls pass freely between them so that each telephone on any national PSTN can reach any other telephone in the world.

Inspec keywords: telephone networks; telecommunication networks; telephone sets

Other keywords: world telecommunications economics; telephone call; PSTN; public switched telephone network; telecommunications technology

Subjects: Telephony