What technology is plain old telephone service (POTS) built on?

Plain Old Telephone Service (POTS) is built on circuit switching technology. This method establishes a dedicated communication path or circuit between two endpoints for the duration of the call. During a POTS call, this circuit is reserved exclusively for the conversation, allowing for a constant and consistent connection between the caller and recipient, which is key for maintaining voice quality.

Circuit switching contrasts with packet switching, where data is broken into packets and sent over a shared network, allowing multiple communications to occur simultaneously but potentially leading to variable delays and packet loss. Technologies like frame relay operate on packet-switched models as well. Voice over Internet Protocol (VoIP) involves digitizing voice signals and sending them over packet-switched networks, which is fundamentally different from the dedicated circuit established by POTS.

Understanding the underlying technology helps highlight why POTS provides reliable and low-latency voice communication, as well as its limitations in terms of bandwidth and the inability to transmit data or multimedia effectively.