An apparatus and method for forming and enlarging percutaneous penetrations comprises an elongate dilation member which receives an elongate expansion member in an axial lumen thereof. The VoIP telephony device and a service node of the VoIP system each are configured for executing at least one corresponding model object, view object, and controller object of a prescribed network service. Rear blade-use arms have step-like bent portions formed therein so that a tip end side of the arms is positioned further toward the base plate than the rotation center side.