WebRTC
WebRTC is a set of browser and application technologies for capturing and sending real-time audio, video, and data over an internet connection. It lets a website or app establish live media sessions without requiring a traditional phone line or a separate browser plug-in.
How WebRTC works
The application asks for permission to use a microphone or camera, negotiates media capabilities with the remote endpoint, and finds a viable network path. Direct connectivity is preferred when possible; relay infrastructure can carry the media when firewalls or network address translation prevent a direct path.
WebRTC does not prescribe the application's signaling system. A service still needs a way to exchange session descriptions, authentication, and call-state messages before media can flow. Once connected, audio is encoded with a mutually supported codec, divided into real-time media packets, and protected in transit. The receiving side reorders and plays those packets while adapting to changing network conditions.
For a browser-to-phone call, a gateway bridges the WebRTC session to SIP or the public telephone network. That bridge may terminate one media leg, translate signaling, and transcode audio when the browser and phone network do not share a codec. The call can therefore be secure on each transport leg without being a single uninterrupted peer-to-peer connection.
Why WebRTC matters for AI phone calls
WebRTC makes browser microphone tests, web-based agent previews, and embedded voice experiences possible. It also introduces conditions that differ from an ordinary phone call: the user's browser permissions, headset, local network, firewall, and active tab can all affect the session.
When testing an AI phone agent in a browser, separate media-path problems from agent behavior. Choppy incoming audio may come from packet loss or jitter; silence may come from a denied microphone permission; one-way audio may point to connectivity or gateway configuration. Test on the browsers and networks users actually have, then test the phone route separately when production calls will travel through the telephone network.