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.
OpenAI's smaller open-weights model, served by Groq at low reasoning effort.
| Scope | pass^5 | pass@1 | E / M / H | Tools | Handoff | Final DB | TTFT | Cost/hr |
|---|---|---|---|---|---|---|---|---|
| Cross-industry | 13.3% | 34.5% | 77 / 28 / 19 | 36.6% | 67.8% | 57.4% | 657ms | $0.073 |
| Healthcare | 18.3% | 39.0% | 97 / 39 / 10 | 39.0% | 69.7% | 70.3% | 617ms | $0.091 |
| Legal | 1.7% | 21.7% | 37 / 21 / 15 | 25.7% | 73.0% | 33.3% | 649ms | $0.069 |
| Customer support | 20.0% | 42.7% | 98 / 24 / 33 | 45.0% | 60.7% | 68.7% | 790ms | $0.059 |
E / M / H is pass@1 on easy, medium, and hard tasks. Gate columns are the share of conversations that cleared each check.