Working paper / 2026
Conversational AI LLM Bench
Abstract
We define conversational AI LLMs as the language models at the center of cascaded voice pipelines, between speech recognition and speech synthesis, that return a first token within one second: a median time to first token of 1,000 ms or less. The Conversational AI LLM Bench (CALLM) benchmarks this category. Each model operates every agent of a multi-agent front desk in healthcare, legal, and customer support, with production-length prompts, executable tools, and per-call database state. A simulated caller pursues a locked task over a simulated phone line, so the model receives only what a speech recognizer would have transcribed, errors included. A deterministic verifier scores tool calls, handoffs, and final database state; pass@1 and pass5 measure single-attempt capability and five-attempt reliability.
Clone the repository, point a model at an industry pack, and reproduce the evaluation environment.
Alibaba's open-weights Qwen3.6 mixture-of-experts model with 3B active parameters, thinking off.
| Scope | pass^5 | pass@1 | E / M / H | Tools | Handoff | Final DB | TTFT | Cost/hr |
|---|---|---|---|---|---|---|---|---|
| Cross-industry | 12.2% | 39.9% | 72 / 32 / 32 | 40.8% | 70.5% | 68.8% | 310ms | $0.032 |
| Healthcare | 15.0% | 37.0% | 87 / 33 / 16 | 37.0% | 66.7% | 76.3% | 321ms | $0.036 |
| Legal | 6.7% | 39.7% | 40 / 35 / 44 | 40.3% | 83.7% | 57.7% | 302ms | $0.038 |
| Customer support | 15.0% | 43.0% | 88 / 28 / 35 | 45.0% | 61.0% | 72.3% | 307ms | $0.021 |
E / M / H is pass@1 on easy, medium, and hard tasks. Gate columns are the share of conversations that cleared each check.