In this paper, the authors are designed and implemented for mobile phone signal jammer for GSM, CDMA with prescheduled time duration using Mobile jammer and ARM7. The jamming device broadcasts an RF signal in the frequency range reserved for cell phones that interferes with the cell phone signal, which results in a "No network available" display on the cell phone screen. All phones within the effective radius of the jammer are silenced. The activation and deactivation time schedules can be programmed with microcontroller. Real time clock chip DS1307 is used to set the schedule.