Evaluating enterprise voice agents: caller simulation choices swing accuracy by 5%

rdesh26 · x · 2026-10-31

How do you evaluate enterprise voice agents (EVAs)? Human evals are ideal but can't cover every checkpoint. The emerging standard—pioneered by Tau-Voice and adopted by EVA, MIVAS, and Vamos—has three steps:

The catch: real recordings are static while dialogs branch endlessly, so another model (cascaded or end-to-end) must simulate the caller—making eval results a function of how that caller is built. Tau-Voice runs standard and custom leaderboards, and GPT-Live shows a 5% accuracy gap between them.

The author argues this isn't merely a harness difference: a model whose task completion varies wildly across caller simulations will likely behave erratically in the real world, where callers can't be controlled—yet models also shouldn't be penalized for caller-side errors like TTS misreading phone numbers.

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