Gemini 3.8 Live Extended Thinking vs Grok Voice 3.0

Grok Voice 3.0 is more reliable, by 18.6 points. Gemini 3.8 Live Extended Thinking handled 17 of 70 real callers well on all three runs, and Grok Voice 3.0 30. A caller only counts when every run of the call scored 80 or more.

For a voice agent, Grok Voice 3.0, since it handles more real callers well on every run. Grok Voice 3.0 is ahead of Gemini 3.8 Live Extended Thinking on ELO rating, hearing score, turn taking score, speaking score, task handling score, reliability, calls handled well, calls fully resolved, calls where the agent went quiet and median latency.

Grok Voice 3.0, by 11.9 points higher. Gemini 3.8 Live Extended Thinking fully resolved 22.9% of calls and Grok Voice 3.0 34.8%. A call counts only when every step the caller needed was done.

No. Grok Voice 3.0 starts replying 0.50s sooner at the median. Gemini 3.8 Live Extended Thinking takes 2.10s at the median and 2.60s at p90; Grok Voice 3.0 takes 1.60s and 1.94s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.

Grok Voice 3.0, by 10.5 points. The agent went quiet for 10 seconds or more on 17.6% of Gemini 3.8 Live Extended Thinking calls and 7.1% of Grok Voice 3.0 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.