Summary

Adds a native xAI Realtime + Plivo example for phone-based speech-to-speech agents.

What's included

• adds xai-realtime-native example
• supports inbound and outbound call flows
• keeps the audio bridge native with Plivo Audio Streaming
• adds README setup and troubleshooting guidance
• wires send_sms to the live Plivo SMS API
• keeps the other example tools available in the same pattern as the existing examples

Validation

• placed inbound test calls (Indian Plivo Number) successfully
• placed outbound test calls (US Plivo Number) successfully
• verified xAI realtime session setup and audio bridge flow
• verified live send_sms capability