Provided is a system for providing mobile telecommunication services using an Internet network built with a UTP cable. The system includes a main unit and a plurality of sub units. The main unit includes a plurality of input ports respectively connected to corresponding distributing ports of the switching hubs through UTP cables, is connected to an external mobile telecommunication base station through a wireless link, combines Internet signals transmitted from the distributing ports of the switching hubs with mobile telecommunication signals transmitted from the mobile telecommunication state through a wireless link. Each sub unit includes an input port connected to corresponding one of the output ports of the main unit through an UTP cable, separates the combined signal from the output port of the main unit into an Internet signal and a mobile telecommunication signal.