CekuraBench
All comparisons
xAIPhonic

Grok Voice Think Fast 2.0 vs Phonic v1

Grok Voice Think Fast 2.0 is ahead on success rate, data accuracy, interruption and cost, and Phonic v1 on agent responses, stalled calls and response time. The two tie on reliability.

Compare

Success rate by suite

Appointments59 scenariosMedicare23 scenarios
  • GPT Realtime 2.1OpenAI
    92%
    81%
  • GPT-Live 1 + Sol lowOpenAI
    97%
    49%
  • Gemini 3.8 Live ThinkingGoogle
    82%
    61%
  • Grok Think Fast 2.0xAI
    96%
    25%
  • Gemini 3.1 Flash LiveGoogle
    93%
    32%
  • Phonic v1Phonic
    97%
    14%
  • Realtime 2.1 MiniOpenAI
    84%
    4%
  • Nova 2 SonicAmazon
    80%
    6%
  • Cascade, GPT-4.1Not ranked
    97%
    83%
Each model's share of calls that passed every check, on each suite.

Every metric, side by side

Reliability

Scenarios that passed on all three runs.

Grok Think Fast 2.0
67.1%3rd
Phonic v1
67.1%3rd

Level

Success rate

Calls that passed every check.

Grok Think Fast 2.0
76.0%4th
Phonic v1
74.0%6th

Grok Think Fast 2.0, 2.0 points higher

Agent responses

Calls where the agent's replies reached the expected outcome.

Grok Think Fast 2.0
96.7%4th
Phonic v1
98.0%3rd

Phonic v1, 1.2 points higher

Data accuracy

Calls where everything the agent saved matched exactly.

Grok Think Fast 2.0
78.9%5th
Phonic v1
74.3%6th

Grok Think Fast 2.0, 4.6 points higher

Stalled calls

Calls where the agent went silent for 10 seconds or more.

Grok Think Fast 2.0
4.5%7th
Phonic v1
0.0%1st

Phonic v1, 4.5 points lower

Interruption

How well it handled being talked over, 0 to 5.

Grok Think Fast 2.0
4.925th
Phonic v1
4.888th

Grok Think Fast 2.0, 0.04 higher

Response time

Median time to start replying after the caller finishes.

Grok Think Fast 2.0
1.62s2nd
Phonic v1
1.59s1st

Phonic v1, 0.04s sooner

Cost / min

One minute of call at the vendor's published rates.

Grok Think Fast 2.0
$0.0804th
Phonic v1
$0.1406th

Grok Think Fast 2.0, $0.060 cheaper

The small figure is the place among ranked models. The cascade is not ranked.

Phonic v1 answers first

Phonic v1 1.59s, Grok Think Fast 2.0 1.62s at the median.

Response time, median to p90

MedianTo p90
Medianp90
  • Phonic v1Phonic
    Phonic v1: median 1.59s, p90 1.86s
    1.59s1.86s
  • Grok Think Fast 2.0xAI
    Grok Think Fast 2.0: median 1.62s, p90 1.94s
    1.62s1.94s
  • GPT Realtime 2.1OpenAI
    GPT Realtime 2.1: median 1.94s, p90 2.46s
    1.94s2.46s
  • GPT-Live 1 + Sol lowOpenAI
    GPT-Live 1 + Sol low: median 2.02s, p90 2.42s
    2.02s2.42s
  • Realtime 2.1 MiniOpenAI
    Realtime 2.1 Mini: median 2.08s, p90 2.75s
    2.08s2.75s
  • Nova 2 SonicAmazon
    Nova 2 Sonic: median 2.18s, p90 2.76s
    2.18s2.76s
  • Gemini 3.8 Live ThinkingGoogle
    Gemini 3.8 Live Thinking: median 2.32s, p90 3.06s
    2.32s3.06s
  • Gemini 3.1 Flash LiveGoogle
    Gemini 3.1 Flash Live: median 2.88s, p90 4.00s
    2.88s4.00s
  • Cascade, GPT-4.1Not ranked
    Cascade, GPT-4.1: median 2.17s, p90 2.51s
    2.17s2.51s
2.0s3.0s4.0s
Seconds from the caller finishing to the agent starting to reply, per model.

What we saw on the calls

Grok Voice Think Fast 2.0

  • Quick, with the shortest replies of the field; steady on the short form.
  • Struggles on the long form: fields left out or wrong, usually an earlier reference.
  • Every stall was on a long form.
Model
grok-voice-think-fast-2.0
Setting
Reasoning high
Voice
eve
Turn taking
Service turn detection
Audio
24 kHz
Cost
Excludes a text-input charge the vendor lists without a unit.

Phonic v1

  • Level with the best on the short form, run after run.
  • Quickest to reply: no late reply, no stalled call.
  • Fails the long form's exact check: it fills in optional fields it should leave out, though the record would usually match.
  • Short-form slips are an extra tool call; it repeats calls more than most.
Model
phonic_v1
Setting
Intelligence high
Voice
sabrina
Turn taking
Service turn detection
Audio
16 kHz
Cost
The vendor's Starter plan rate per conversation minute, applied to each call's length; the Pro plan is $0.12.
See the full leaderboardReference agent

Related comparisons

Frequently asked questions

Is Grok Voice Think Fast 2.0 or Phonic v1 more reliable?

Grok Voice Think Fast 2.0 passed 55 of 82 scenarios on all three runs, and Phonic v1 passed 55. That is level.

Which saves caller data more accurately, Grok Voice Think Fast 2.0 or Phonic v1?

Grok Voice Think Fast 2.0 saved everything exactly right on 78.9% of the calls that save data, and Phonic v1 on 74.3%. On Appointments, 97.1% against 98.2%. On Medicare, 31.8% against 12.1%. A call counts only when nothing is missing, wrong, extra or saved twice.

Which responds faster, Grok Voice Think Fast 2.0 or Phonic v1?

Phonic v1 starts replying 0.04s sooner at the median. Grok Voice Think Fast 2.0 takes 1.62s at the median and 1.94s at p90; Phonic v1 takes 1.59s and 1.86s. Both are measured on the call audio, from the caller finishing to the agent starting to reply.

Which costs less, Grok Voice Think Fast 2.0 or Phonic v1?

Grok Voice Think Fast 2.0 costs $0.080 a minute of call and Phonic v1 $0.140, at each vendor's published rates. Grok Voice Think Fast 2.0 is $0.060 cheaper a minute.

How were Grok Voice Think Fast 2.0 and Phonic v1 compared?

Both ran as the whole agent in the same open-source Pipecat pipeline, with the same prompt, tools and phone line. A simulated caller worked through all 82 scenarios on live calls, three times each, 2,214 calls across the benchmark. A call passes only when the agent said the right things and saved the right data.