Terminal-error counts do not establish voice outage coverage

Terminal model-error counts and telemetry heartbeats cover different failure mechanisms from caller progress. A request can remain pending until the caller cancels; excluding normal cancellation is useful for noise control but can also leave an outage with little terminal-error evidence. An unconditional metrics heartbeat can continue while admission dependencies or delivered audio fail. Choose the next paging signals by matching historical customer symptoms to actual observable stages, and calibrate thresholds on independently identified healthy periods. Count distinct affected calls where available; raw request totals and mismatched numerator/denominator lifetimes do not establish service-wide impact.