Meta Tech ProviderGlossary
SIP Trunking for Voice AI
SIP trunking lets a voice AI platform send and receive phone calls over the internet, connecting to the PSTN via a carrier like Twilio or Plivo.
Definition
SIP (Session Initiation Protocol) trunking is how voice AI platforms connect to the public phone network. A SIP trunk is a virtual phone line over the internet, provided by a carrier like Twilio, Plivo, Exotel or Telnyx. The voice AI platform sends and receives calls through the SIP trunk, and the carrier handles the actual PSTN connectivity. For Indian deployments, SIP trunks must be paired with DLT-registered caller IDs to be compliant.
How SIP trunking works with voice AI
When a phone call arrives at your SIP trunk (inbound) or your voice AI agent wants to dial out (outbound), the audio is streamed over the SIP trunk as RTP packets. The voice AI platform plugs into this stream, runs STT + LLM + TTS in real time, and sends the agent's audio back over the trunk. Modern voice AI platforms like ThinnestAI handle the SIP complexity automatically.
Why it matters
SIP trunking is what separates a voice AI agent you can only reach through a web page from a voice AI agent you can reach by dialing a real +91 phone number. Without SIP, there is no phone call.
Glossary
More definitions
Want to see voice AI in action?
Talk to a live voice agent in your browser — no signup, pick your language.