NMIJ has been giving calibration service of time and frequency standards. At present, the client must carry their frequency standards (DUT = Device under Test) into our laboratory. Therefore, DUT must be stopped and suffer disturbances caused by carrying. And furthermore, the frequency of DUT is never calibrated in usual circumstances. Then, new calibration system using GPS (= Global Positioning System) and the Internet is developed in NMIJ. This system consists of two processes as follows; 1) frequency measurement using GPS common-view technique and 2) data transfer from client to NMIJ via the Internet. We have tested the validity of this system by experiment.