# What is the PSTN (Public Switched Telephone Network)?

The PSTN (Publicly Switched Telephone Network) is the network that carries your voice calls when you call from a landline or cell phone. It refers to the worldwide network of voice-carrying telephone infrastructure, including privately-owned and government-owned infrastructure.

The PSTN is the network that carries voice calls, and interfacing between the internet and the PSTN has traditionally been very costly and difficult. The Twilio Programmable [Voice API](https://www.twilio.com/en-us/voice) abstracts this complexity away, giving developers verbs like [\<Dial>](/docs/voice/twiml/dial) and \<Conference> to execute what have been extremely difficult voice calling tasks in the past.