Phone Voice Agent：实时AI电话代理，集成语音转录与TTS

Run a real-time AI phone agent using Twilio, Deepgram, and ElevenLabs. Handles incoming calls, transcribes audio, generates responses via LLM, and speaks back via streaming TTS. Use when user wants to: (1) Test voice AI capabilities, (2) Handle phone calls programmatically, (3) Build a conversational voice bot.