Gemini 3.1 Flash Live Preview vs GPT Realtime 2.1

GPT Realtime 2.1 is more reliable, by 17.1 points. Gemini 3.1 Flash Live Preview passed 51 of 82 scenarios on all three runs, and GPT Realtime 2.1 passed 65. A scenario only counts when every run of it passed.

For a voice agent, GPT Realtime 2.1, since it gets more scenarios right on every run. GPT Realtime 2.1 is ahead on reliability, success rate, agent responses, data accuracy and response time, and Gemini 3.1 Flash Live Preview on cost. The two tie on calls where the agent went quiet and interruption.

GPT Realtime 2.1, by 12.7 points. Gemini 3.1 Flash Live Preview saved everything exactly right on 79.2% of the calls that save data, and GPT Realtime 2.1 on 92.0%. On Booking calls, 96.5% against 95.9%. On Medicare calls, 34.8% against 81.8%. A call counts only when nothing is missing, wrong, extra or saved twice.

No. GPT Realtime 2.1 starts replying 0.94s sooner at the median. Gemini 3.1 Flash Live Preview takes 2.88s at the median and 4.00s at p90; GPT Realtime 2.1 takes 1.94s and 2.46s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.

They score the same. Gemini 3.1 Flash Live Preview scores 4.98 and GPT Realtime 2.1 4.98 for how well the agent handled being talked over.

They go quiet on the same share of calls. The agent went quiet for 10 seconds or more on 3.3% of Gemini 3.1 Flash Live Preview calls and 3.3% of GPT Realtime 2.1 calls.

Gemini 3.1 Flash Live Preview is $0.0150 cheaper a minute. Gemini 3.1 Flash Live Preview costs $0.0703 a minute of call and GPT Realtime 2.1 $0.0853, at each vendor's published rates.

Cekura ran both as the whole agent in the same open-source Pipecat pipeline, with the same prompt, tools and connection. A simulated caller worked through all 82 scenarios on live calls, three times each, 3,690 calls across the benchmark. A call passes only when the agent said the right things and saved the right data.