A tandem switch, also known as Class 4 switch or TDM switch, is a type of telephone central office switch that connects telco end offices and allows them to communicate with each other while being disconnected from the client. It is a computer system specifically designed for TDM-based, circuit-switched phone calls and is commonly used by telecommunication companies worldwide, with Lucent and Nortel Networks being some of the most frequently used brands.
Tandem switches were once mainly responsible for call recording and invoicing but have since been replaced by end office switches. Access tandem switches connect end offices and POPs for interexchange carriers, while sector tandem switches connect end offices for intraLATA traffic (IXCs).
In the past, Class 4 tandem switches only supported high-speed, four-wire T1, T3, and OC-3 connections. Nowadays, all switches are designed to support four-wire lines to accommodate various telecommunications requirements.
FAQs about Tandem Switches
What is the difference between a tandem switch and an end office switch?
Tandem switches connect telco end offices and remain disconnected from the client, while end office switches typically handle the local connections to customers.
Why were tandem switches mainly responsible for call recording and invoicing in the past?
Tandem switches were designed to track long-distance calls that crossed from one end office to another, making it efficient to monitor call duration and calculate charges accordingly.
What types of connections do Class 4 tandem switches support?
In the past, Class 4 tandem switches only supported high-speed, four-wire T1, T3, and OC-3 connections. Nowadays, all tandem switches are designed to support four-wire lines to accommodate various telecommunications requirements.
Conclusion
Tandem switches are a critical component of the telecommunication industry, connecting end offices and facilitating communication among telco companies for intraLATA and interexchange traffic. With high-speed connectivity and advanced features, these switches provide vital services for modern telephony.
