diff --git a/src/Plugins/BotSharp.Plugin.Twilio/Hooks/TwilioConversationHook.cs b/src/Plugins/BotSharp.Plugin.Twilio/Hooks/TwilioConversationHook.cs
index cb1dad813..3505e73d8 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/Hooks/TwilioConversationHook.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/Hooks/TwilioConversationHook.cs
@@ -3,7 +3,7 @@
 using BotSharp.Abstraction.Routing.Models;
 using BotSharp.Plugin.Twilio.Interfaces;
 using BotSharp.Plugin.Twilio.Models;
-using Twilio.Rest.Api.V2010.Account;
+using BotSharp.Plugin.Twilio.Services;
 using Task = System.Threading.Tasks.Task;
 
 namespace BotSharp.Plugin.Twilio.Hooks;
@@ -57,10 +57,7 @@ public override async Task OnFunctionExecuted(RoleDialogModel message, InvokeFun
                 // Save all states before reconnect
                 await states.Save();
 
-                CallResource.Update(
-                    pathSid: sid,
-                    url: new Uri(processUrl));
-
+                await _services.GetRequiredService<TwilioService>().TryRedirectCallAsync(sid, processUrl);
                 break;
             }
         }
diff --git a/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/HangupPhoneCallFn.cs b/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/HangupPhoneCallFn.cs
index aea4d2df2..6aa5ae27b 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/HangupPhoneCallFn.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/HangupPhoneCallFn.cs
@@ -3,7 +3,6 @@
 using BotSharp.Core.Infrastructures;
 using BotSharp.Plugin.Twilio.OutboundPhoneCallHandler.LlmContexts;
 using BotSharp.Plugin.Twilio.Services;
-using Twilio.Rest.Api.V2010.Account;
 
 namespace BotSharp.Plugin.Twilio.OutboundPhoneCallHandler.Functions;
 
@@ -42,20 +41,18 @@ public async Task<bool> Execute(RoleDialogModel message)
         }
 
         var processUrl = $"{_twilioSetting.CallbackHost}/twilio/voice/hang-up?agent-id={message.CurrentAgentId}&conversation-id={conversationId}";
+        var twilio = _services.GetRequiredService<TwilioService>();
 
         // Generate initial assistant audio
         if (!string.IsNullOrEmpty(args.ResponseContent) && _twilioSetting.GenerateEndingAudio)
         {
-            var twilio = _services.GetRequiredService<TwilioService>();
             var initAudioFile = await twilio.SaveSpeechAsync(conversationId, "ending", args.ResponseContent);
 
             processUrl += $"&init-audio-file={initAudioFile}";
         }
 
-        var call = CallResource.Update(
-            url: new Uri(processUrl),
-            pathSid: callSid
-        );
+        // A call that already ended is what hanging up wants, so it still counts as hung up
+        await twilio.TryRedirectCallAsync(callSid, processUrl);
 
         message.Content = args.Reason;
         message.StopCompletion = true;
diff --git a/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/TransferPhoneCallFn.cs b/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/TransferPhoneCallFn.cs
index 71aa9c5a5..33d494361 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/TransferPhoneCallFn.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/TransferPhoneCallFn.cs
@@ -4,7 +4,6 @@
 using BotSharp.Core.Infrastructures;
 using BotSharp.Plugin.Twilio.OutboundPhoneCallHandler.LlmContexts;
 using BotSharp.Plugin.Twilio.Services;
-using Twilio.Rest.Api.V2010.Account;
 
 namespace BotSharp.Plugin.Twilio.OutboundPhoneCallHandler.Functions;
 
@@ -47,19 +46,22 @@ public async Task<bool> Execute(RoleDialogModel message)
         var conversationId = routing.Context.ConversationId;
         var processUrl = $"{_twilioSetting.CallbackHost}/twilio/voice/transfer-call?agent-id={routing.Context.EntryAgentId}&conversation-id={conversationId}&transfer-to={args.PhoneNumber}";
 
+        var twilio = _services.GetRequiredService<TwilioService>();
+
         // Generate initial assistant audio
         if (!string.IsNullOrEmpty(args.TransitionMessage))
         {
-            var twilio = _services.GetRequiredService<TwilioService>();
             var initAudioFile = await twilio.SaveSpeechAsync(conversationId, "transfer", args.TransitionMessage);
 
             processUrl += $"&init-audio-file={initAudioFile}";
         }
 
         // Transfer call
-        var call = CallResource.Update(
-            pathSid: sid,
-            url: new Uri(processUrl));
+        if (!await twilio.TryRedirectCallAsync(sid, processUrl))
+        {
+            message.Content = "The phone call has already ended, so it was not transferred.";
+            return false;
+        }
 
         message.Content = args.TransitionMessage;
         return true;
diff --git a/src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioService.cs b/src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioService.cs
index 9c1ef3e3b..f798eb6ba 100644
--- a/src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioService.cs
+++ b/src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioService.cs
@@ -6,7 +6,9 @@
 using BotSharp.Plugin.Twilio.Interfaces;
 using BotSharp.Plugin.Twilio.Models;
 using BotSharp.Plugin.Twilio.Models.Relay;
+using Twilio.Exceptions;
 using Twilio.Jwt.AccessToken;
+using CallResource = Twilio.Rest.Api.V2010.Account.CallResource;
 using Twilio.Rest.Api.V2010.Account.Call;
 using Task = System.Threading.Tasks.Task;
 using Token = Twilio.Jwt.AccessToken.Token;
@@ -423,6 +425,30 @@ public async Task<string> SaveSpeechAsync(string conversationId, string name, st
         return fileName;
     }
 
+    /// <summary>
+    /// Points a live call at new TwiML. Returns false when the call is no longer in progress (Twilio 21220): the caller
+    /// already hung up, or the message did not come from a live call at all (e.g. a phone conversation continued over
+    /// the REST API). Any other Twilio error is thrown.
+    /// </summary>
+    public async Task<bool> TryRedirectCallAsync(string callSid, string url)
+    {
+        try
+        {
+            await CallResource.UpdateAsync(pathSid: callSid, url: new Uri(url));
+            return true;
+        }
+        catch (ApiException ex) when (ex.Code == CallNotInProgressErrorCode)
+        {
+            _logger.LogInformation($"Call {callSid} is no longer in progress, not redirected: {ex.Message}");
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// Twilio's "Call is not in-progress. Cannot redirect.",see https://www.twilio.com/docs/api/errors/21220
+    /// </summary>
+    private const int CallNotInProgressErrorCode = 21220;
+
     /// <summary>
     /// Returns the file name of a speech saved by SaveSpeechAsync, whichever mode it was saved in.
     /// </summary>