Efficient Out-of-Scope Detection in Dialogue Systems via Uncertainty-Driven LLM Routing

Álvaro Zaera, Diana Nicoleta Popa, Ivan Sekulic, Paolo Rosso


Abstract
Out-of-scope (OOS) intent detection is a critical challenge in task-oriented dialogue systems (TODS), as it ensures robustness to unseen and ambiguous queries. In this work, we propose a novel but simple modular framework that combines uncertainty modeling with fine-tuned large language models (LLMs) for efficient and accurate OOS detection. The first step applies uncertainty estimation to the output of an in-scope intent detection classifier, which is currently deployed in a real-world TODS handling tens of thousands of user interactions daily. The second step then leverages an emerging LLM-based approach, where a fine-tuned LLM is triggered to make a final decision on instances with high uncertainty.Unlike prior approaches, our method effectively balances computational efficiency and performance, combining traditional approaches with LLMs and yielding state-of-the-art results on key OOS detection benchmarks, including real-world OOS data acquired from a deployed TODS.
Anthology ID:
2025.acl-industry.25
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 6: Industry Track)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Georg Rehm, Yunyao Li
Venue:
ACL
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Publisher:
Association for Computational Linguistics
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Pages:
328–335
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URL:
https://preview.aclanthology.org/landing_page/2025.acl-industry.25/
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Cite (ACL):
Álvaro Zaera, Diana Nicoleta Popa, Ivan Sekulic, and Paolo Rosso. 2025. Efficient Out-of-Scope Detection in Dialogue Systems via Uncertainty-Driven LLM Routing. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 6: Industry Track), pages 328–335, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Efficient Out-of-Scope Detection in Dialogue Systems via Uncertainty-Driven LLM Routing (Zaera et al., ACL 2025)
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https://preview.aclanthology.org/landing_page/2025.acl-industry.25.pdf