Inception released Mercury Voice, a model built to power AI phone agents and voice assistants. It is a diffusion model, which means it does not write one word at a time the way most chatbots do. Instead it starts with a rough draft and refines the whole answer at once, so the first word is ready almost immediately. On real customer-service prompts, Inception measured a median 320 milliseconds to that first answer word, with the slowest 5% under 750 milliseconds, 5.9 times faster than GPT-6 Luna with reasoning turned off. The company says Mercury Voice also beats Gemma 4 31B, GLM-5.3-Flash, and Qwen3.5-397B across tool-use and conversation tests. It holds 128,000 tokens of context, runs at three reasoning levels, and ships as a drop-in, OpenAI-compatible API.
In a voice agent, the pause after you stop talking is the whole product. Wait past about half a second and the call feels broken, so most voice bots use fast models that skip real reasoning. Mercury Voice reasons and still answers inside that window. Audivi AI runs drive-thru ordering on it, Altur handles bank payment calls, and OpenCall reported a median response near 170 milliseconds in production. Launch pricing is $0.20 per million input tokens and $0.75 per million output, about $0.009 per minute of conversation.
The mechanism is architectural. Standard models write one word at a time, so more thinking means more waiting. Diffusion models generate many words in parallel, which is how Mercury Voice can reason and still stay fast.
Read More: Gemini 3.8 Live: Voice Models That Think While They Talk
Sources:
- Introducing Mercury Voice (Inception)
- Introducing Mercury 2.5 (Inception)
- Our Models: Mercury pricing and specs (Inception)
- Inception Launches Mercury 2.5, the Next Tier of Intelligence for Diffusion LLMs (Business Wire)
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Citation
@misc{kabui2026,
author = {{Kabui, Charles}},
title = {Mercury {Voice:} {A} {Voice} {AI} {That} {Reasons} {Without}
the {Awkward} {Pause}},
date = {2026-10-05},
url = {https://toknow.ai/posts/inception-mercury-voice-diffusion-llm-voice-agents/},
langid = {en-GB}
}