I have enhancement suggestion to make which is based on a Raspberry Pi project I was reading about recently.
Have a mode where it only allow white listed number.
In order to maintain the whitelist OOMA would have to ask the caller to enter a certain code which would be told as part of the message, the caller would then enter that code and his number would be added to the whitelist. After that the caller would have to call again and then the call would go thru.
Example:
Caller: dial my number
OOMA: Hello, please enter the code 832 to add your number to the white list, once accepted, any subsequent call from the same originating number will got thru automatically.
Caller: 832
OOMA: Thank you, your number as been added to the list. Please hangup and call again to complete your call.
Caller: hangup
Caller: dial my number
OOMA: yes this number on my white list so let it ring...