AI-103: Developing AI Apps and Agents on Azure

Custom Speech models and their deployed endpoints follow a defined lifecycle with an expiration date. When a custom model reaches that date, the associated custom endpoint does not shut down or begin returning errors; instead, the Speech service automatically falls back to using the most recent base model for the same locale, so recognition requests keep succeeding, only losing the custom adaptation rather than failing outright. The endpoint is not deleted automatically, and expired custom models are not retained indefinitely for continued use without manual intervention.