Abstract: The present disclosure addresses the problem of providing a method for decomposing a crosslinked rubber that can improve monomer yield. The solution is a method of decomposing a crosslinked rubber that includes: a first decomposition step of pyrolyzing a crosslinked rubber containing a diene rubber at a temperature of 150° C. or more and 400° C. or less, and a second decomposition step of pyrolyzing a decomposition product obtained by the first decomposition step under an inert gas atmosphere and in the presence of a catalyst at a temperature of 300° C. or more and 950° C. or less. Preferably 80 mass % or more of the diene rubber in the crosslinked rubber is decomposed to diene oligomers having a weight-average molecular weight of 100 to 50,000 via the first decomposition step.

Abstract: In a mobile communication system of the present invention, a cordless base unit LBU is connected to a wired subscriber line SL. The base unit LBU detects a radio channel assigned to a cell other than a cell where the base unit LBU is located, among radio channels assigned to the cells of a cellular radio communication system. This radio channel is used as a radio channel for a cordless call. On the other hand, a cellular cordless telephone CCT is provided with a mode switch. When a cordless mode is designated by the mode switch, a radio channel for a cordless call is detected, as with the case of the base unit LBU. At the time of the cordless call, a transmission power level of the cellular cordless telephone CCT is set at a weak level smaller than that for a cellular call.