PolyAI is ahead on repeatable reliability, task completion, infrastructure reliability, tool call accuracy, interruption handling and response time, and Vapi on voice tone and clarity.

PolyAI ranked 1 of 10 · Vapi ranked 8 of 10

Last updated Methodology by Luis Ojeda

Which to pick

Pick PolyAI for reliability across repeated runs (28.04 points higher), completing the caller's task (1.22 points higher), calls that connect and stay up (16.26 points higher), accurate tool calls (0.88 higher), handling interruptions (0.26 higher) and fast replies (0.62s faster). Pick Vapi for how the agent sounds (0.11 higher).

Every metric, side by side

Bars share one scale across all 10 platforms. The place next to each figure is its rank in the field.

Repeatable reliability

Share of the 82 scenarios that passed on all three runs.

PolyAI
87.80%1st
Vapi
59.76%8th

PolyAI, 28.04 points higher

Task completion

Calls where the expected outcome was fully reached.

PolyAI
98.78%1st
Vapi
97.56%2nd

PolyAI, 1.22 points higher

Infrastructure-clean calls

Calls with no connection, audio or platform failure.

PolyAI
99.19%3rd
Vapi
82.93%9th

PolyAI, 16.26 points higher

Tool call accuracy

Mean score for calling the right tool with the right arguments.

PolyAI
4.90/51st
Vapi
4.02/510th

PolyAI, 0.88 higher

Voice tone and clarity

Mean score for how clear and natural the agent sounds.

PolyAI
3.97/58th
Vapi
4.08/57th

Vapi, 0.11 higher

Interruption handling

Mean score for yielding and recovering when the caller cuts in.

PolyAI
4.99/52nd
Vapi
4.73/59th

PolyAI, 0.26 higher

Mean response time

Mean time for the agent to start replying after the caller stops.

PolyAI
2.46s6th
Vapi
3.08s10th

PolyAI, 0.62s faster

246 calls per platform: 82 scenarios, 3 runs each.

What each platform ran, and what we saw

PolyAI

Strength
Leads repeatable reliability at 87.80% pass³ and task completion at 98.78% across all 246 calls.
What can be improved
Mean response time is 2.46s and voice tone and clarity is 3.97/5. Repetition and call termination were not scored; tool accuracy covers 237 calls and response time covers 245.
STT, LLM and TTS
  • Component versions not supplied with these results

Vapi

Strength
Tied for second in task completion at 97.56% across 205 calls with outcome evidence.
What can be improved
The remaining 41 of 246 calls did not connect and remain visible in infrastructure reliability.
STT, LLM and TTS
  • stt-rt-v5
  • gpt-4.1-2025-04-14
  • vapi-v2 (Clara)

PolyAI vs Vapi FAQ

  • PolyAI is more reliable, by 28.04 points. PolyAI passed 87.80% of the 82 scenarios on all 3 runs and Vapi passed 59.76%. A scenario only counts when every run of it passed.

  • PolyAI starts replying sooner, 0.62s faster. Mean response time is 2.46s for PolyAI and 3.08s for Vapi.

  • PolyAI reached the expected outcome on 98.78% of calls and Vapi on 97.56%. PolyAI is ahead on task completion.

  • Both ran the same Appointment and Medicare agents through the same 82 caller scenarios, 3 times each, with the same evaluators and mock tools. Only the platform and its speech and model components changed.

Test your voice agent the same way.

Cekura runs these simulated calls on your agent and scores every one.