Voice Call MCP Server
by lukaskai
A Model Context Protocol (MCP) server that enables Claude and other AI assistants to initiate and manage voice calls using Twilio and OpenAI (GPT-4o Realtime model). Use this as a base to kick-start your AI-powered voice calling explorations, save time and develop additional functionality on top of it.
Last updated: N/A
What is Voice Call MCP Server?
This is a Model Context Protocol (MCP) server that allows AI assistants like Claude to make and manage phone calls. It uses Twilio for call management and OpenAI's GPT-4o Realtime model for real-time audio processing and conversation.
How to use Voice Call MCP Server?
- Clone the repository, 2. Install dependencies (Node.js >= 22, Twilio account, OpenAI API key, Ngrok Authtoken), 3. Configure environment variables, 4. Configure Claude Desktop to connect to the server, 5. Interact with Claude using natural language to initiate calls.
Key features of Voice Call MCP Server
Make outbound phone calls via Twilio
Process call audio in real-time with GPT-4o Realtime model
Real-time language switching during calls
Pre-built prompts for common calling scenarios
Automatic public URL tunneling with ngrok
Secure handling of credentials
Use cases of Voice Call MCP Server
Making simple phone calls
Making restaurant reservations
Scheduling appointments
Any task requiring voice communication initiated by an AI assistant
FAQ from Voice Call MCP Server
Phone number must be in E.164 format
Phone number must be in E.164 format
Make sure the phone number starts with '+' and the country code
Invalid credentials
Invalid credentials
Double-check your TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN. You can copy them from the Twilio Console
OpenAI API error
OpenAI API error
Verify your OPENAI_API_KEY is correct and has sufficient credits
Ngrok tunnel failed to start
Ngrok tunnel failed to start
Ensure your NGROK_AUTHTOKEN is valid and not expired
OpenAI Realtime does not detect the end of voice input, or is lagging.
OpenAI Realtime does not detect the end of voice input, or is lagging.
Sometimes, there might be voice encoding issues between Twilio and the receiver's network operator. Try using a different receiver.