From c89ad76ddb5cbe2bef14cfb0f396ac6b24980d10 Mon Sep 17 00:00:00 2001
From: Haiping Chen <hchen@lessen.com>
Date: Tue, 1 Apr 2025 14:30:44 -0500
Subject: [PATCH] OnCallBusyStatus

---
 .../Controllers/TwilioVoiceController.cs                 | 4 ++++
 .../Interfaces/ITwilioCallStatusHook.cs                  | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioVoiceController.cs b/src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioVoiceController.cs
index 2a1c7cd0..6078dd7b 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioVoiceController.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioVoiceController.cs
@@ -348,6 +348,10 @@ public class TwilioVoiceController : TwilioController
                 await HookEmitter.Emit<ITwilioCallStatusHook>(_services, x => x.OnUserDisconnected(request));
             }
         }
+        else if (request.CallStatus == "busy")
+        {
+            await HookEmitter.Emit<ITwilioCallStatusHook>(_services, x => x.OnCallBusyStatus(request));
+        }
 
         return Ok();
     }
diff --git a/src/Plugins/BotSharp.Plugin.Twilio/Interfaces/ITwilioCallStatusHook.cs b/src/Plugins/BotSharp.Plugin.Twilio/Interfaces/ITwilioCallStatusHook.cs
index bbc243c3..899cc526 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/Interfaces/ITwilioCallStatusHook.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/Interfaces/ITwilioCallStatusHook.cs
@@ -10,4 +10,13 @@ public interface ITwilioCallStatusHook
     Task OnRecordingCompleted(ConversationalVoiceRequest request);
     Task OnTranscribeCompleted(ConversationalVoiceRequest request);
     Task OnVoicemailStarting(ConversationalVoiceRequest request);
+
+    /// <summary>
+    /// 1. The recipient's phone line is already engaged.
+    /// 2. Some users block unknown or spam calls, which may cause a "busy" status.
+    /// 3. Some carriers explicitly return a busy signal instead of routing the call to voicemail.
+    /// </summary>
+    /// <param name="request"></param>
+    /// <returns></returns>
+    Task OnCallBusyStatus(ConversationalVoiceRequest request);
 }