The Whisper action plays a recording made by the caller to a transfer target while the caller is on hold. While listening to the recording and prompts the transfer target can either accept the call by pressing 1 or reject the call by pressing any other key or hanging up.
The caller recording is obtained by a Voice Question or Listen action preceding the Whisper action. The Whisper action also sets several text items for display on the transfer target extension and for prompts to be played before and after the caller's recording.
You can use the action without requiring a recording. The transfer target decides whether to accept or reject the call based on the displayed information and the prompts if they have been setup. Voicemail also accepts the whisper call transfer automatically after the recording (if any) and after prompts have been played to the transfer target.