Twilio SMS and MMS C# .NET Quickstart

This collection of C# .NET Quickstarts will take you through all the steps you'll need to add SMS and MMS capabilities to your .NET web application. We've collected here quickstarts to take you through many common SMS and MMS scenarios, such as threading SMS conversations, sending and receiving messages, and sending messages concurrently with voice and video calls.

Code and examples are included for usage of the Twilio C# Helper Library as well as Twilio REST API endpoints.


Twilio Programmable SMS allows you to:

  1. Receive SMS and MMS messages to your Twilio phone numbers and reply back with SMS and MMS messages
  2. Send SMS and MMS messages using Twilio's REST API
  3. Track SMS conversations
  4. Send SMS messages during phone calls

Send SMS and MMS Messages Via the REST API

You can also send SMS messages using Twilio's REST API. To send a message, just make an HTTP POST to Twilio with the body of the message and the phone number you want to send it to. SMS messages must be sent from Twilio SMS-enabled phone numbers due to the architecture of the global SMS network.

Receive and Reply to SMS Messages

When you buy an SMS-enabled Twilio phone number, you can associate that phone number with an SMS URL. When someone sends a text message to that phone number, Twilio makes an HTTP request to your URL with the body of the message and the sender's phone number. You can then respond to the SMS by returning a reply message in the HTTP response to Twilio.

Track SMS Conversations

Using standard HTTP cookies, you can share state across multiple messages allowing you to treat separate messages between any pair of phone numbers as a conversation, and store data about the conversation in the cookie for future reference.

Send SMS Messages During Phone Calls

You can also use the TwiML <Message> verb inside your existing Twilio voice calls to send a message during a phone conversation.

Frequently asked Questions

For specific details on what you can and can't accomplish using Twilio SMS please refer to the SMS FAQ


You'll need a SMS-enabled Twilio phone number for sending and receiving messages. You can use a free Twilio trial account and get your own dedicated Twilio phone number.

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