Below is the free and opensource schematic diagram of cell phone jammer. This circuit is designed for building a cell phone jammer which could blocking mobile phone signals works on GSM1900 band, also called DCS. The defined blocking frequency is downlink of GSM1900, from 1930MHz to 1990MHz. The GSM1900 mobile phone network is used by USA, Canada and most of the countries in South America. This cell phone jammer is not applicable for use in Europe, Middle East, nor Asia.