WebSocket calls, especially in the context of VoIP (Voice over Internet Protocol) and web-based real-time communication, work somewhat differently from traditional telephony. In WebSocket calls, the communication happens over a WebSocket protocol, which is a web technology providing full-duplex communication channels over a single TCP connection. Here’s a basic rundown:

How WebSocket Calls Work

1. Connection Establishment: A WebSocket connection is initiated from a client (such as a web browser or a mobile app) to a server. This connection remains open, allowing two-way communication without the need for repeatedly establishing new connections for each message or voice packet.
2. Real-Time Communication: Once the WebSocket connection is established, audio (and potentially video) data can be sent in real-time between the client and the server. This is typically done using media streaming protocols like WebRTC (Web Real-Time Communication), which work alongside WebSocket for real-time media transmission.
3. WebSocket as Signaling: In many VoIP applications, WebSocket is used for signaling – setting up, controlling, and terminating calls. The actual media (voice/video) is often transmitted via different protocols like RTP (Real-Time Protocol) in combination with WebRTC.

From and To Numbers

• Traditional Calls: In conventional telephony, each call has a “From” and a “To” number, representing the caller and the callee.
• WebSocket Calls: For WebSocket or Internet calls, the concept of a phone number may not be necessary or is abstracted differently. Instead, the communication is typically between a user/client and a server/application.
  • From: Could be an identifier like a user ID, a session ID, or a device ID instead of a traditional phone number.
  • To: Often a server endpoint or a specific URI (Uniform Resource Identifier) rather than a phone number. In the context of APIs or server-based applications, this could be the address to which the WebSocket connects for sending and receiving data.

Usage Scenarios

• Web-based Communication: Applications like web conferencing tools, browser-based VoIP phones, or chat applications.
• App-to-Server Communication: Mobile or desktop applications that communicate with a server for voice/video chat functionalities.

WebSocket-based communication is particularly powerful for creating seamless, real-time, bidirectional communication experiences in web and mobile applications, without the limitations and structures of traditional telephony.