Lists the callback requests waiting in a call center's queue, oldest first, so the first result has been waiting longest. Each callback reports the number to call back, when it was queued, and a status that is either "queued" while the request is still waiting for an operator or "timed_out" once it waited longer than the call center's max_hold_seconds. Queued callbacks carry their position in the queue; timed-out ones do not. The API key must have admin rights on the specified call center; this is a per-call-center check rather than a company-wide admin requirement.

Rate limit: 1200 per minute.