Gemini 3.1 Flash Live Preview vs Gemini 3.8 Live Extended Thinking

Gemini 3.1 Flash Live Preview is more reliable, by 10.0 points. Gemini 3.1 Flash Live Preview handled 24 of 70 real callers well on all three runs, and Gemini 3.8 Live Extended Thinking 17. A caller only counts when every run of the call scored 80 or more.

For a voice agent, Gemini 3.1 Flash Live Preview, since it handles more real callers well on every run. Gemini 3.1 Flash Live Preview is ahead on ELO rating, hearing score, task handling score, reliability, calls handled well, calls fully resolved and calls where the agent went quiet, and Gemini 3.8 Live Extended Thinking on median latency. The two tie on turn taking score and speaking score.

Gemini 3.1 Flash Live Preview, by 1.9 points higher. Gemini 3.1 Flash Live Preview fully resolved 24.8% of calls and Gemini 3.8 Live Extended Thinking 22.9%. A call counts only when every step the caller needed was done.

No. Gemini 3.8 Live Extended Thinking starts replying 0.96s sooner at the median. Gemini 3.1 Flash Live Preview takes 3.06s at the median and 3.86s at p90; Gemini 3.8 Live Extended Thinking takes 2.10s and 2.60s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.

Gemini 3.1 Flash Live Preview, by 10.0 points. The agent went quiet for 10 seconds or more on 7.6% of Gemini 3.1 Flash Live Preview calls and 17.6% of Gemini 3.8 Live Extended Thinking 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.