In this guide we’ll show you how to manipulate live phone calls using C#. We’ll also cover how to retrieve information about in progress and completed calls from your Twilio account.
The code snippets in this guide are written using modern C# language features and require the .NET Framework version 4.5 or higher. They also make use of the Twilio C# SDK.
The simplest way to control the flow of a Twilio phone call is with TwiML itself.
You can use the "action" parameters of verbs like <Gather> and <Record> to tell Twilio to get new instructions from your applications during a call. You can also use the <Redirect> verb to explicitly tell Twilio to fetch new TwiML.
But sometimes you need to change a live phone call outside of Twilio’s normal request-response cycle. For those cases you can use "RedirectCall()" to tell Twilio to immediately change the TwiML it’s using in a phone call.
To update a call in progress you must provide:
- CallSid - Twilio returns a CallSid when you initiate an outgoing call. Twilio also includes the CallSid in its request to your application for an incoming call’s initial TwiML.
- Url - The URL Twilio should use to request new TwiML from your application.
Check out Modifying Live Calls in the reference docs for more details.