A circuit switch is a type of telecommunications network that establishes a dedicated communication channel between two parties for the duration of a call. It operates by creating a physical circuit or a virtual path between the sender and receiver, allowing them to communicate directly over this dedicated connection. This process can be better understood through the following steps:
Call setup: When a user initiates a call (e.g., by dialing a phone number), the circuit switch system receives the request. The system then checks the availability of resources and determines whether a circuit can be established between the calling party (A) and the called party (B).
Circuit establishment: If resources are available, the circuit switch system sets up the dedicated circuit between parties A and B. This circuit ensures that the two parties have exclusive use of the communication path for the duration of the call.
Data transfer: Once the circuit is established, data (voice or other forms of information) can be transmitted between A and B. Since the circuit is dedicated, there is no need for packet routing or addressing during the call. Data can flow smoothly and continuously between the two endpoints.
Call termination: When the call is complete, either party can terminate the communication. Upon call termination, the dedicated circuit is released, and the resources that were assigned for the call are freed up and made available for other calls.
Circuit switches were commonly used in traditional telephone networks, where physical connections were established through copper wires. They ensured a stable and uninterrupted connection during the call but also had some limitations, such as fixed bandwidth allocation and a high cost for maintaining idle circuits.
With the advent of digital networks and the internet, circuit-switched networks have been largely replaced by packet-switched networks, such as those based on the Internet Protocol (IP). Packet-switched networks, including Voice over IP (VoIP), utilize data packets to transmit voice and other forms of data. They are more efficient in utilizing network resources, as they allow multiple communications to share the same infrastructure simultaneously.