[li-zhou-dev]

With Say on, the reconnect prompt and the hang-up and transfer lines of a realtime call were spoken with Say, while the model speaks with its own voice, so the caller heard two voices in one call.

• AppendSpeech(preferRecording) plays a prerecorded prompt as recorded even when its text is configured in PromptTexts. The prompts queued before the realtime stream and the prompt of a stream reconnect use it.
• SaveSpeechAsync(preferAudio) synthesizes the mp3 even when Say is on. The hang-up and transfer functions ask for it when the call is a realtime call (TwilioService.IsRealtimeCall).
• TwilioInboundController records the mode once, by the label of the agent that took the call, as the call state twilio_realtime_call, so a routing to an agent without the label does not change it.

Calls that are not realtime behave as before.

[qodo-code-review]

Code Review by Qodo

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[qodo-code-review]

PR Summary by Qodo

Play recorded prompts and synthesized speech on realtime Twilio calls

🐞 Bug fix ✨ Enhancement 🕐 20-40 Minutes

AI Description

• Play recorded prompts before realtime streams and during reconnects, even when Say is enabled.
• Synthesize hang-up and transfer lines for realtime agents instead of using Twilio Say.
• Preserve existing speech behavior for non-realtime calls.

Diagram

graph TD
  Prompts["Stream prompts"] --> Append["AppendSpeech"] --> Play["TwiML Play"]
  Actions["Hang-up or transfer"] --> Label{"Realtime agent?"} --> Save["SaveSpeechAsync"] -->|standard text| Say["TwiML Say"]
  Save -->|realtime MP3| Play

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High-Level Assessment

The following are alternative approaches to this PR:

1. Track speech mode in call state

• ➕ Reflects the mode chosen when the call started, even if the current agent changes.
• ➕ Avoids fetching agent metadata when preparing a hang-up or transfer line.
• ➖ Requires call-state propagation and lifecycle handling.
• ➖ Adds complexity for calls without established state.

Recommendation: The label-based approach matches inbound realtime routing and keeps this fix localized. If calls can switch agents, verify that CurrentAgentId still represents the call's stream mode; otherwise, call-level state would be safer.

Files changed (4) +33 / -11

Enhancement (1) +28 / -8

TwilioService.csAdd realtime speech playback preferences +28/-8

Add realtime speech playback preferences

• Adds opt-in overrides for playing recorded prompts and synthesizing MP3s when Say is enabled. Applies recorded playback to prompts queued before bidirectional streams and adds an agent-label lookup for hang-up and transfer decisions.

src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioService.cs

Bug fix (3) +5 / -3

TwilioReconnectController.csPlay the recorded reconnect prompt +1/-1

Play the recorded reconnect prompt

• Requests recorded playback for the reconnect prompt instead of allowing configured prompt text to trigger Say.

src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioReconnectController.cs

HangupPhoneCallFn.csSynthesize realtime hang-up speech +2/-1

Synthesize realtime hang-up speech

• Checks whether the current agent is realtime and requests an MP3 for its generated ending line.

src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/HangupPhoneCallFn.cs

TransferPhoneCallFn.csSynthesize realtime transfer speech +2/-1

Synthesize realtime transfer speech

• Checks whether the current agent is realtime and requests an MP3 for its transfer announcement.

src/Plugins/BotSharp.Plugin.Twilio/OutboundPhoneCallHandler/Functions/TransferPhoneCallFn.cs

[Copilot]

🟡 Changes recommended

Transfer and hang-up messages can still use Say during an active realtime call because audio preference is derived from the current agent’s label rather than the active call/session mode.

1 open issue

• Use active session mode to select audio for transferred calls · New

What changed in this PR

This PR updates Twilio speech handling to avoid switching to Twilio Say for prompts and closing messages during realtime calls.

Changes:

• Prefer recordings for prompts before realtime streams and during reconnects.
• Allow speech synthesis even when SayGeneratedSpeech is enabled.
• Use the current agent’s realtime label to request synthesized hang-up and transfer messages.

File	Description
src/​Plugins/​BotSharp.Plugin.Twilio/​Services/​TwilioService.cs	Adds audio preferences and realtime-agent detection.
src/​Plugins/​BotSharp.Plugin.Twilio/​OutboundPhoneCallHandler/​Functions/​TransferPhoneCallFn.cs	Requests audio for realtime-agent transfer messages.
src/​Plugins/​BotSharp.Plugin.Twilio/​OutboundPhoneCallHandler/​Functions/​HangupPhoneCallFn.cs	Requests audio for realtime-agent ending messages.
src/​Plugins/​BotSharp.Plugin.Twilio/​Controllers/​TwilioReconnectController.cs	Prefers recordings for reconnect prompts.

_{Review effort: Balanced}

[yileicn]

reviewed