xAI's Grok Voice Agent is a real-time WebSocket API with full-duplex audio, 100+ languages, and ~$0.05 per minute — built for marketers who want to automate the boring half of phone work without burning out their SDR team.
Five frontier models, five different superpowers. After running them side by side on real campaigns for six months, here's which one I open for which marketing job — and the brand-safety landmine that makes Grok-Imagine unusable for most brands.
