Implement DTMF recognition functionality for enhanced call interaction

[Copilot]

Overview

This PR implements comprehensive DTMF (Dual-Tone Multi-Frequency) recognition functionality to enable interactive voice response (IVR) capabilities in the ACSforMCS telephony system. The implementation follows the existing architectural patterns and provides seamless integration with the current caller identification and bot conversation infrastructure.

Key Features

Enhanced CallContext

• Added DtmfSequence property to store recognized DTMF tones (0-9, *, #)
• Added HasDtmfInput boolean flag to track DTMF availability
• Implemented thread-safe AddDtmfTone() method for real-time sequence building
• Enhanced GetDataQuality() method to consider DTMF input in data completeness assessment

New DtmfExtractor Service

Created a comprehensive DTMF processing service following the same pattern as CallerInfoExtractor:

• Robust extraction from Azure Communication Services RecognizeCompleted events
• Support for all standard DTMF tones with proper validation
• Comprehensive error handling and status tracking
• Utility methods for sequence validation and formatting

Event Processing Integration

• Added RecognizeCompleted event handler in the webhook endpoint
• Automatic DTMF information extraction and CallContext updates
• Real-time forwarding of DTMF input to bot conversations
• Enhanced logging for debugging and monitoring

Usage Example

When a caller presses phone keys during a call, the system now:

1. Captures the DTMF tones automatically through Azure Communication Services events
2. Stores the sequence in the CallContext (e.g., "123*#")
3. Forwards to the bot in the format: DTMF_INPUT=5|DTMF_SEQUENCE=12345
4. Enables bot routing based on keypad input for menu navigation and authentication

// CallContext now provides DTMF information
if (callContext.HasDtmfInput)
{
    var sequence = callContext.DtmfSequence; // "123*#"
    var quality = callContext.GetDataQuality(); // "complete" when DTMF available
}

Benefits

• Enhanced user experience through interactive phone menu systems
• Automated routing based on caller keypad input
• Authentication capabilities via PIN or code entry
• Department selection through numeric menu options
• Seamless bot integration for advanced conversation flows

Backward Compatibility

• All existing functionality preserved without breaking changes
• No modifications to existing API contracts
• Follows established patterns and conventions
• Thread-safe implementation ensures stability

Testing

• Added development test endpoint (/test/dtmf) for functionality verification
• Comprehensive error handling for edge cases
• Detailed logging for production monitoring
• Complete documentation with integration examples

This enhancement significantly expands the system's telephony capabilities while maintaining the existing architecture and ensuring reliable operation in production environments.

This pull request was created as a result of the following prompt from Copilot chat.

The goal is to enhance the DTMF (Dual-Tone Multi-Frequency) recognition functionality in the ACSforMCS repository. Specifically, the system should handle DTMF recognition in a way similar to how Caller ID detection is implemented. This includes:

• Adding a mechanism to capture and process DTMF sequences during a call.
• Storing the recognized DTMF sequence in the CallContext in the same way Caller ID information is stored.
• Ensuring that the DTMF data can be accessed and utilized by downstream processes, such as routing or interaction logic.
• Updating relevant classes and services, such as CallContext, CallerInfoExtractor, or any event handlers that might be necessary for capturing DTMF input.
• Providing appropriate logging and error handling for DTMF detection.

This will enable the system to personalize interactions or make decisions based on the recognized DTMF input, enhancing the overall functionality and usability of the telephony system.

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