The Voice Agent Stack

The five-layer build map for AI voice agents. Telephony, ASR, LLM, TTS, orchestration. Real prices, real latency budgets, the questions that separate a serious agency from a packager.

• Real per-minute prices for Twilio, Telnyx, Plivo, Vonage, and Bandwidth, with the STIR/SHAKEN rules that decide answer rate
• STT, TTS, and LLM picks for live voice in 2026, with the latency budget that gets you to 1,200 ms mouth-to-ear on telephony
• The system prompt skeleton, warm transfer pattern, owner checklist, and word-for-word brief to send the agency