*78: Activates the do not disturb feature
From PhonePower Knowledge Base
This will Enable the Do Not Disturb Feature.
You will still be able place outbound calls, but your phone will function as if Busy when an inbound call tries to call your Phone Power phone number.
To use:
Pick up the Phone Power phone.
Once you hear a dial tone, dial *78.
Hang up the Phone Power Phone.
- Note - While this feature is Enabled, your Phone Power phone will not ring.