MDVPN (Mobile Data Virtual Private Network), by using CHT Mobile network as the transmission interface, creates a private mobile data network custom made just for the enterprise. It can also extend the internal network functions or collocate with a specific application service, allowing the staff to receive or send necessary information through the virtual private network anytime, anywhere to achieve the objective of strengthening the competitivity. By using this wireless network to retrieve internal resources or specific application services, the cost of fixed line can be reduced and the function of enterprise group setting is offered to ensure the safety of enterprise network via GSM digital identification.