OptionalawaitingWhat the host is waiting for RIGHT NOW (R3-307) — present only while a host prompt is actually up. Prefer it over reason when rendering: "tap your passkey" is a sentence the user can act on; "this may need you" is not.
OptionalreasonWhy this call may be waiting on a person — present only when attended. It comes from the classification table, so it is a standing possibility, not a live fact.
What
onPendingis told when a call is taking a while.