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.
Anthropic's fastest Claude model.
| Scope | pass^5 | pass@1 | E / M / H | Tools | Handoff | Final DB | TTFT | Cost/hr |
|---|---|---|---|---|---|---|---|---|
| Cross-industry | 62.2% | 83.2% | 97 / 84 / 76 | 84.1% | 95.7% | 92.4% | 963ms | $0.206 |
| Healthcare | 60.0% | 80.3% | 100 / 85 / 66 | 81.0% | 97.0% | 92.3% | 1.01s | $0.219 |
| Legal | 58.3% | 85.7% | 90 / 87 / 83 | 85.7% | 97.0% | 89.7% | 1.14s | $0.182 |
| Customer support | 68.3% | 83.7% | 100 / 80 / 79 | 85.7% | 93.0% | 95.3% | 601ms | $0.217 |
E / M / H is pass@1 on easy, medium, and hard tasks. Gate columns are the share of conversations that cleared each check.