# OpenAI SIP API for Voice Calls

> Connect phone calls to AI voice services using SIP trunking.
- Title: OpenAI SIP API for Voice Calls · OpenAI Developers | Shortify
- Summary: Connect phone calls to AI voice services using SIP trunking. OpenAI's SIP API lets businesses route phone calls through AI voice services with real-time…
- Keywords: openai, sip, gpt-live, realtime api, voice calls, sip trunking, webhooks, call control, delegation, audio processing, OpenAI Developers
- Source: OpenAI Developers — https://developers.openai.com/api/docs/guides/voice-sip
- Read time: 1 min
- Topics: openai, sip, gpt-live, realtime api, voice calls, sip trunking, webhooks, call control, delegation, audio processing, technology, startups
## GPT-Live Realtime API
Connect incoming and outgoing phone calls to GPT-Live through a SIP trunk.
## Handle inbound calls
Receive incoming-call webhook, then accept or reject the call.
## Place outbound calls
Create session to dial phone number through your provider.
## Use sideband connection
Attach to existing conversation for session events or commands.
## Configure phone number
Use sip trunking provider like twilio to connect phone number.
## SIP signaling
SIP signaling uses tls, gpt-live requires srtp for call audio.
## Receive incoming call
Webhook sends live.transport.incoming event when call arrives.
## Accept or reject call
Send authenticated post request to accept or reject call.
## Attach backend
Connect sideband websocket after call acceptance.
## Outbound call setup
Provider handles phone network connection while gpt-live carries conversation.
## SIP trunk configuration
Supply transport.destination and trunk provider details.
## Create session
Send post request with session configuration and transport type.
## Monitor call events
Track transport.ringing, answered, failed events.
## Manage active call
Send keypad tones, transfer calls, or hang up.
## SIP network requirements
Allow tcp/tls traffic to sip.api.openai.com on port 5061.
## Next steps
Use prompting guide, webhooks, delegation and tools.
## Key takeaway

OpenAI's SIP API lets businesses route phone calls through AI voice services with real-time transcription and call control.