Estimated reading time: 5 minutes

Circuit-Switched Networks

A circuit-switched network is a communication system in which a dedicated end-to-end path is established between two endpoints before data transmission begins. Once created, this circuit remains exclusively reserved for the duration of the session and is released when communication ends.

Circuit switching formed the architectural foundation of early telecommunications systems and shaped the development of global voice networks. Although packet-switched systems now dominate modern data networking, circuit switching remains essential for understanding how communication infrastructure evolved.

This article is maintained as a general reference on circuit-switched networks and is updated periodically to reflect the current industry context.

What Is a Circuit-Switched Network?

In a circuit-switched network, communication begins only after the network has allocated all required resources between the sender and the receiver. These resources include switching capacity and transmission paths that remain committed for the entire session.

Because the circuit is reserved in advance, performance characteristics such as latency and bandwidth remain stable throughout communication. This predictable behavior made circuit switching particularly well-suited for real-time voice transmission.

Understanding this model requires examining how the network is structured and how connections are established.

Architecture of Circuit-Switched Networks

A circuit-switched network consists of interconnected switching nodes linked by transmission paths that together create a continuous communication circuit.

Key architectural components include:

• Endpoints, which initiate and receive communication
• Local switching nodes, which connect endpoints to the network
• Intermediate or tandem switching nodes, which route traffic between regions
• Core switching nodes, which manage long-distance and high-capacity connections
• Transmission paths, which become exclusively reserved once a circuit is established

When a session begins, the network selects a route through these switching layers and allocates the necessary capacity along each segment. This reserved path forms a continuous circuit that remains active until the session is terminated.

How Circuit Switching Works

The operational sequence of circuit switching follows a defined process:

1. A connection request is initiated
2. Switching nodes analyze addressing information
3. A complete end-to-end route is selected
4. Resources along that route are reserved
5. Communication begins
6. The circuit is released when the session ends

Because resources are allocated in advance, data flows without interruption or path changes during the session.

Evolution of Circuit-Switched Technologies

Circuit switching developed alongside the expansion of telephone networks. Early implementations relied on manual switchboards where operators physically connected calls. As demand increased, electromechanical switching systems automated this process. Later, digital switching technologies improved scalability and control while preserving the dedicated circuit model.

Over time, hybrid architectures emerged that combined circuit-oriented call control with newer transmission technologies. Despite these changes, the fundamental principle of reserving a dedicated path remained consistent.

Circuit Switching in the PSTN and POTS

The largest implementation of circuit switching is found in the Public Switched Telephone Network, commonly known as the PSTN. For decades, the PSTN used circuit-switched architecture to establish dedicated paths for every telephone call.

Within this system, switching exchanges created continuous circuits across multiple network layers, ensuring consistent voice quality and predictable performance.

Plain Old Telephone Service, or POTS, represents the subscriber-level analog voice service delivered over this circuit-switched infrastructure. While POTS describes the service experienced by users, the PSTN refers to the broader network architecture that enables it.

In practical terms:

• Circuit switching defines the connection model
• The PSTN represents the large-scale implementation of that model
• POTS refers to the traditional voice service delivered over it

Although modern transport mechanisms have evolved, circuit switching shaped the design and operation of global telephony networks for much of the twentieth century.

Advantages and Limitations

Circuit-switched networks offer several advantages:

• Predictable latency
• Stable bandwidth allocation
• Consistent performance for real-time communication
• Straightforward quality-of-service behavior

However, these strengths come with tradeoffs:

• Bandwidth remains reserved even during idle periods
• Infrastructure costs are substantial
• Scalability is limited compared to packet-based networks

As communication expanded beyond voice to include data-intensive applications, these limitations encouraged the adoption of packet switching.

Modern Relevance

Although pure circuit-switched networks are less common today, the model continues to influence modern systems. Circuit-oriented logic persists in certain legacy telephony environments and in hybrid network implementations that integrate traditional control mechanisms with newer transmission technologies.

Studying circuit switching provides foundational insight into network engineering principles such as resource allocation, connection management, and quality of service.

Common Misconceptions About Circuit-Switched Networks

Frequently Asked Questions

Last updated: February 2026

• Powerful POTS Replacement for Data Centers
• T1/PRI Replacement Services
• Copper Retirement and Its Impact on Commercial Real Estate
• Cutting Table Load Times by 80% through Smarter Search Performance and Aggregate Views
• FCC Sets the Ground Rules for the POTS Shut Down