Abstract: The present invention provides a mobile telephone capable of establishing connection to the Internet or the like only by operating a side key with a simplified connecting operation and reduced time required for connection. A portable telephone as a mobile telephone includes an Internet connecting function, a telephone function, other various functions, a side key provided for a side face of the body to execute a specific function, a display provided for an operation face, and a memory storing information including telephone numbers and URLs. When the side key is depressed long, a controller displays the URLs read from the memory in a list format onto the display and establishes connection to one URL selected from the list by the side key.

Abstract: Optical regenerative relay amplifier 102 has a function for monitoring the power of optical signals from an optical fiber 101, and issuing an optical signal trouble detection signal (AIS (Alarm Indication Signal)) for shutting down the optical power in case that optical signal inputs are lost, and notifying the trouble, and optical ADMs 103 have a wavelength path selecting function, a wavelength path bundle function, and a wavelength path trouble or quality monitoring function in addition to an AIS issue function, and the optical cross-connect systems 104 have an AIS issue function, a function for monitoring a trouble or quality deterioration of optical signals for every wavelength path, a wavelength path grooming function, and a wavelength path protection function, and the terminal stations 105 transmit and receive services by optical signals having predetermined wavelengths, and monitoring a trouble or quality deterioration of optical signals for every wavelength path is conducted without depending on signa