Twiliohttps://twilio.comSMS/voice/WhatsApp APIs. awesome-llm-apps collectionhttps://github.com/Shubhamsaboo/awesome-llm-appsCurated LLM app collection — RAG, agents, voice, MCP examples. Voice RAG agent (awesome-llm-apps)https://github.com/Shubhamsaboo/awesome-llm-apps/tree/main/voice_ai_agents/voice_rag_openaisdkExample: voice + retrieval agent.