Uploaded December 2025 | Updated September 2026, 17 minutes ago
Send a fun, pre‑recorded greeting or musical message with a real MP3 file—not text‑to‑speech—using Twilio Voice and .NET.
In this step‑by‑step tutorial, you’ll learn how to attach an MP3 to an automated outbound phone call so your friends, family, or customers hear a custom audio message when they pick up.
In this video, you’ll learn how to:
- Set up a Twilio account and purchase a voice‑enabled phone number
- Upload your MP3 file to Twilio Assets and get a public URL
- Create a new .NET 9 console app and install the Twilio .NET SDK
- Securely store your Account SID and Auth Token with .NET user‑secrets
- Use Twilio Voice to place an automated call and play your MP3 using TwiML Play
- Test the call to your own smartphone
What you need (prerequisites):
- A free or paid Twilio account
- An operating system that supports .NET (Windows, macOS, or Linux)
- .NET 9 SDK installed
- A code editor or IDE (VS Code, Visual Studio, Rider, etc.)
- An MP3 audio file
- A smartphone with active cellular service
FAQs:
Q: How do I attach an MP3 to an automated Twilio voice call in .NET?
A: Upload your MP3 to Twilio Assets (or another public host), copy the file URL, then use the Twilio .NET SDK to create a call with TwiML that contains a Play action pointing to your MP3 URL.
Q: Can I use this to send pre‑recorded messages to customers?
A: Yes. Once your code is set up, you can call any verified phone number and play a pre‑recorded MP3 message, making it easy to send announcements, alerts, or seasonal greetings at scale.
Ready to build your first musical message with Twilio and .NET?
Watch the tutorial, grab the sample code, and start sending MP3‑powered voice calls today.
Blog Post here: twil.io/voice-mp3
#Twilio #TwilioVoice #DotNET #CSharp #VoiceAPI #TwilioTutorial #DeveloperTutorial #AutomatedCalls #MP3 #PreRecordedMessage
💻 Sign up for a Twilio account here: twil.io/trytwilio-yt
👉 Subscribe for more Twilio updates: twil.io/sub-twiliodevs
Chapters:
00:00 Intro
00:14 Prerequisites
00:41 Phone Numbers in Twilio Console
01:11 Account SID and Auth Token
01:30 Uploading MP3 to Assets
02:05 Writing the Application
02:34 Adding the Twilio CLI
02:47 Setting Environment Variables
03:04 Updating Program.cs
03:55 Running the Application
Send a fun, pre‑recorded greeting or musical message with a real MP3 file—not text‑to‑speech—using Twilio Voice and .NET.
In this step‑by‑step tutorial, you’ll learn how to attach an MP3 to an automated outbound phone call so your friends, family, or customers hear a custom audio message when they pick up.
In this video, you’ll learn how to:
- Set up a Twilio account and purchase a voice‑enabled phone number
- Upload your MP3 file to Twilio Assets and get a public URL
- Create a new .NET 9 console app and install the Twilio .NET SDK
- Securely store your Account SID and Auth Token with .NET user‑secrets
- Use Twilio Voice to place an automated call and play your MP3 using TwiML Play
- Test the call to your own smartphone
What you need (prerequisites):
- A free or paid Twilio account
- An operating system that supports .NET (Windows, macOS, or Linux)
- .NET 9 SDK installed
- A code editor or IDE (VS Code, Visual Studio, Rider, etc.)
- An MP3 audio file
- A smartphone with active cellular service
FAQs:
Q: How do I attach an MP3 to an automated Twilio voice call in .NET?
A: Upload your MP3 to Twilio Assets (or another public host), copy the file URL, then use the Twilio .NET SDK to create a call with TwiML that contains a Play action pointing to your MP3 URL.
Q: Can I use this to send pre‑recorded messages to customers?
A: Yes. Once your code is set up, you can call any verified phone number and play a pre‑recorded MP3 message, making it easy to send announcements, alerts, or seasonal greetings at scale.
Ready to build your first musical message with Twilio and .NET?
Watch the tutorial, grab the sample code, and start sending MP3‑powered voice calls today.
Blog Post here: twil.io/voice-mp3
#Twilio #TwilioVoice #DotNET #CSharp #VoiceAPI #TwilioTutorial #DeveloperTutorial #AutomatedCalls #MP3 #PreRecordedMessage
💻 Sign up for a Twilio account here: twil.io/trytwilio-yt
👉 Subscribe for more Twilio updates: twil.io/sub-twiliodevs
Chapters:
00:00 Intro
00:14 Prerequisites
00:41 Phone Numbers in Twilio Console
01:11 Account SID and Auth Token
01:30 Uploading MP3 to Assets
02:05 Writing the Application
02:34 Adding the Twilio CLI
02:47 Setting Environment Variables
03:04 Updating Program.cs
03:55 Running the Application
