Why can't I use the private line for other network services?

Medicare network is a private computer network, although the contact is far away, but because the client contains the health insurance agency, designated medical institutions and designated retail pharmacies and the basic information of the insured and other types of information, all the insured medical purchase of medicines through the information connected to this network, so the matter is very important, and will never be allowed to connect to the Internet public network, but with the fiber optic dedicated connection of the internal local area network, physically with the public network is not connected, and can not be connected. The public network is not connected, and can not be connected.