PSTN

PSTN (Public Switched Telephone Network), also called Plain Old Telephone Service (POTS), comprises all the circuit-switched, interconnected telephone networks in the world. Originally an analog system that has now turned digital, PSTN establishes dedicated circuits for the duration of phone calls. This is different from packet-switching networks such as internet networks, in which messages are divided into packets and sent via the most efficient route. PSTN remains the foundational global telephone infrastructure that enterprise contact centers connect to via SIP trunks.

For enterprise voice AI deployments, understanding PSTN is important for architects and telephony engineers who need to ensure voice AI systems connect reliably to the global telephone network through the appropriate gateway and trunk configurations.

Key Points

• Global circuit-switched telephone network infrastructure
• Also known as Plain Old Telephone Service (POTS)
• Originally analog, now largely digital
• Establishes dedicated circuits for call duration
• Enterprise contact centers connect to PSTN via SIP trunks

Why It Matters

PSTN is the foundation that all enterprise voice operations — including voice bots, conversational IVR, and agent calls — ultimately connect to when serving customers who call from standard phone numbers. Understanding its role helps architects design reliable voice AI connectivity.

Best-Practice Perspective

Ensure your voice AI platform connects to the PSTN via reliable, redundant SIP trunk providers. Work with your telephony team to understand capacity, failover, and quality of service requirements to ensure your conversational AI voice deployments meet enterprise reliability standards.