# SIP vs WebRTC for voice agents

> SIP connects a voice agent to the normal phone network so it can dial and receive real phone numbers; WebRTC carries voice inside a web browser or app. For calling Indian leads on their phones, SIP with Indian telephony carriers is what matters.

Source: https://agents.elevatebox.in/glossary/sip-vs-webrtc  
Updated: 2026-10-12

## How each one works

SIP (Session Initiation Protocol) is the signalling standard that sets up and ends calls between phone systems; a SIP trunk from a carrier links software to the public phone network. WebRTC is a browser standard for real-time audio and video between a web page or app and a server, with no phone number involved.

## Which one you need

- SIP: for real outbound and inbound phone calls to mobile numbers, the normal case for Indian lead calling
- WebRTC: for in-app or in-browser voice, such as a 'talk to us' button on a website

> India readiness often comes down to SIP integration with Indian carriers and DLT. Tools without India-native telephony struggle here.

## Frequently asked questions

### Do I need a SIP trunk to use an AI voice agent?

Not usually. Business products provide the phone numbers and telephony for you. You need your own SIP trunk only if you build on a developer platform or want to bring numbers you already have.

### Can WebRTC call a mobile number?

Not on its own. WebRTC carries audio between a browser or app and a server. To reach a mobile number, the call has to cross into the phone network through a SIP or telephony gateway.