# How to Connect Your Twilio Agent to External APIs

DevFeed: [How to Connect Your Twilio Agent to External APIs](<https://devfeed.tech/articles/how-to-connect-your-twilio-agent-to-external-apis-31438.md>)

Original publisher: [Read original article](<https://www.twilio.com/en-us/blog/developers/tutorials/product/how-to-connect-twilio-agent-to-external-apis>)

Author: Amanda Lange

Published: 2026-09-15T00:00:00Z

Content type: tutorial

Language: en

Sources: [Twilio Blog](<https://devfeed.tech/sources/twilio-blog.md>)

Topics: [AI Agent](<https://devfeed.tech/topics/ai-agent.md>), [API](<https://devfeed.tech/topics/api.md>), [C#](<https://devfeed.tech/topics/csharp.md>), [.NET 9](<https://devfeed.tech/topics/net-9.md>), [REST API](<https://devfeed.tech/topics/rest-api.md>), [SDKs](<https://devfeed.tech/topics/sdks.md>), [OpenAI](<https://devfeed.tech/topics/openai.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [api](<https://devfeed.tech/tags/api.md>), [apis](<https://devfeed.tech/tags/apis.md>), [c-sharp](<https://devfeed.tech/tags/c-sharp.md>), [developer-insights](<https://devfeed.tech/tags/developer-insights.md>), [environment-variables](<https://devfeed.tech/tags/environment-variables.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [net](<https://devfeed.tech/tags/net.md>), [net-9](<https://devfeed.tech/tags/net-9.md>), [ngrok](<https://devfeed.tech/tags/ngrok.md>), [openai](<https://devfeed.tech/tags/openai.md>), [rest-api](<https://devfeed.tech/tags/rest-api.md>), [sdk](<https://devfeed.tech/tags/sdk.md>)

## AI overview

This tutorial explains how to build a voice AI agent with C# and .NET 9 using Twilio Conversation Relay. It demonstrates LLM tool calling to fetch live data from an external REST API and covers project setup, required packages, environment variables, and API key storage.

## Source excerpt

How to Connect Your Twilio Agent to External APIs