VTech 17850 User Manual page 111

If you press X/DELETE when in idle mode to temporarily
turn off the message alert tone, there is a voice prompt
directing you to press X/DELETE again to delete all old
messages. The message alert tone is temporarily off.
Only press X/DELETE a second time if you wish to erase
all old messages in your answering system.
The message alert tone resumes when you receive
another message.
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