Gemini 3.8 Live Extended Thinking vs Grok Voice Think Fast 2.0

Grok Voice Think Fast 2.0 is more reliable, by 4.3 points. Gemini 3.8 Live Extended Thinking handled 17 of 70 real callers well on all three runs, and Grok Voice Think Fast 2.0 20. A caller only counts when every run of the call scored 80 or more.

For a voice agent, Grok Voice Think Fast 2.0, since it handles more real callers well on every run. Grok Voice Think Fast 2.0 is ahead on ELO rating, hearing score, speaking score, task handling score, reliability, calls where the agent went quiet and median latency, and Gemini 3.8 Live Extended Thinking on turn taking score and calls handled well. The two tie on calls fully resolved.

They are level. Gemini 3.8 Live Extended Thinking fully resolved 22.9% of calls and Grok Voice Think Fast 2.0 22.9%. A call counts only when every step the caller needed was done.

No. Grok Voice Think Fast 2.0 starts replying 0.66s sooner at the median. Gemini 3.8 Live Extended Thinking takes 2.10s at the median and 2.60s at p90; Grok Voice Think Fast 2.0 takes 1.44s and 1.83s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.

Grok Voice Think Fast 2.0, by 9.0 points. The agent went quiet for 10 seconds or more on 17.6% of Gemini 3.8 Live Extended Thinking calls and 8.6% of Grok Voice Think Fast 2.0 calls.

There is no verified per-minute rate for Gemini 3.8 Live Extended Thinking, so cost cannot be compared yet.

Cekura ran both as the whole agent with the same prompt, tools and phone connection. Both took the same 70 recorded real human callers on live calls, three times each. Each call is graded on 25 skills across Hearing, Turn Taking, Task Handling and Speaking, and passes at a score of 80 out of 100.