Clears a voicemail box back to a fresh state: every message and greeting is deleted and the mailbox's stored audio is removed. The mailbox itself survives, keeping its password, other settings, keypad options and copy destinations, while the tutorial flag is turned off and both the selected and alternate greetings are cleared. The reset runs in stages, so a later failure can leave the earlier deletions already done, and audio-cleanup errors are logged without failing the reset. No request body is read.