A trunk call, also known as a long-distance call, is a telecommunications term used to describe a phone call made between two distant locations, typically in different cities, states, or countries. In the past, when telecommunication networks were primarily based on analog systems, trunk calls were manually connected by operators using physical switchboards.
Before the advent of modern digital communication systems and the widespread use of mobile phones, making a trunk call involved the following process:
- The caller would pick up the phone and place a call to a local telephone exchange (also known as a central office) nearest to them.
- The local exchange would then connect the caller to a trunk line, which was a high-capacity line dedicated to handling long-distance calls.
- The call would travel through a series of intermediate exchanges (if required) along the trunk line, each handling a different part of the long-distance route.
- Finally, the call would reach the destination's local exchange, which would then route it to the recipient's telephone number.
Trunk calls were more expensive than local calls because they involved the use of long-distance infrastructure and often required manual intervention by operators. However, with advancements in digital telecommunications and the proliferation of mobile and internet-based communication, the distinction between local and trunk calls has blurred. Nowadays, most phone calls are placed using digital technology, and long-distance calling is often included in phone plans or charged at much lower rates compared to the past.