---
title: "How to Build an RCS Business Messaging Campaign with Twilio in C#"
description: "RCS Business Messaging upgrades SMS with branded conversations featuring images, suggested replies, and read receipts delivered natively on the recipient’s phone. Twilio Programmable Messaging supports RCS via the same API used for SMS, allowing reuse of existing integrations. This tutorial teaches building an RCS campaign in .NET 10, requiring a Twilio account, registered RCS Sender, Messaging Service, ngrok, and a code editor. The process includes creating a rich card template with hero image, dynamic placeholders, and three buttons (Shop the sale, Send promo code, Unsubscribe), then broadcasting personalized messages via the Twilio helper library while capturing status and replies through webhooks exposed by ngrok. Test devices receive messages without waiting for full RCS sender approval, and the server terminal outputs inbound replies and status callbacks in real time."
---

# How to Build an RCS Business Messaging Campaign with Twilio in C#

[Twilio](https://yomu.fyi/company/twilio) · Amanda Lange, Dhruv Patel · Sep 25, 2026

**Type:** Tutorial

## Summary

RCS Business Messaging upgrades SMS with branded conversations featuring images, suggested replies, and read receipts delivered natively on the recipient’s phone. Twilio Programmable Messaging supports RCS via the same API used for SMS, allowing reuse of existing integrations. This tutorial teaches building an RCS campaign in .NET 10, requiring a Twilio account, registered RCS Sender, Messaging Service, ngrok, and a code editor. The process includes creating a rich card template with hero image, dynamic placeholders, and three buttons (Shop the sale, Send promo code, Unsubscribe), then broadcasting personalized messages via the Twilio helper library while capturing status and replies through webhooks exposed by ngrok. Test devices receive messages without waiting for full RCS sender approval, and the server terminal outputs inbound replies and status callbacks in real time.

## Context

SMS lacks rich media and interactivity; RCS provides branded conversations with images, suggested replies, and read receipts. Twilio’s RCS Business Messaging support allows developers to use the same API for both SMS and RCS, but requires proper setup including sender registration and content templates.

## Approach / What changed

Use the Twilio .NET helper library and Content API to create a .NET 10 web application. Register an RCS Sender via Twilio Console, design a rich card Content Template with dynamic variables and action buttons (URL, QuickReply), configure a Messaging Service to use the RCS Sender, and set up status callback and inbound webhooks via ngrok. Send personalized messages to a recipient list and handle replies programmatically.

## Takeaways

- RCS Sender registration requires manual brand review, but test devices can be added to receive messages immediately without waiting for full approval.
- Content Templates use the Content API to define rich cards with dynamic variables, hero images, and action buttons like URL and QuickReply for user interaction.
- Delivery status and inbound replies are captured via webhooks configured in the Twilio Console, and ngrok exposes local endpoints during development.

## FAQ

### How do I register an RCS Sender and test without approval?

Register via Twilio Console under Products & Services > Numbers & Senders > RCS. Add test device numbers to the Tester sender section on the Try it out page to receive messages immediately.

### How do I create a Content Template with dynamic variables?

Use the Content API's ContentResource.CreateAsync with TwilioCard builder. Set WithVariables with a dictionary for placeholders like {{1}}, then pass values at send time.

### What troubleshooting steps help when RCS messages fall back to SMS?

Confirm the recipient's device supports RCS and the RCS Sender is approved or the device is a tester. Verify the phone number is in E.164 format and the Messaging Service has the RCS Sender attached.

**Tags:** [.NET](https://yomu.fyi/topic/dotnet), [RCS](https://yomu.fyi/topic/rcs), [Twilio](https://yomu.fyi/topic/twilio)

- Source: [Twilio](https://www.twilio.com/en-us/blog/developers/tutorials/product/build-rcs-business-messaging-campaign-twilio-csharp)
- Source URL: https://www.twilio.com/en-us/blog/developers/tutorials/product/build-rcs-business-messaging-campaign-twilio-csharp
- Ingested by Yomu: 2026-09-26T18:00:13.216Z

[Read original post](https://www.twilio.com/en-us/blog/developers/tutorials/product/build-rcs-business-messaging-campaign-twilio-csharp)