if all 3 of your devices have different public IP addresses, in other words- your phones are not connected to your wifi but are using their cellular network- then yes they should all three ring.

Ive always had trouble trying to use more than one device on the same internet connection with the same incoming number. But then again I did not go very far into experimentation with port settings en such...

Im sure it can be made to work but can't say myself yet how.