Provided is a method for saving power of a portable device that exists in a location where a fixed telephone network is available, the method including transferring a mobile communication network-based call connection request message transmitted to the portable device into a fixed telephone network-based call connection request message; and receiving the transferred call connection request message in a fixed telephone network support communication module included in the portable device, and forming a fixed telephone network-based call channel in place of the mobile communication network based call.