A security monitoring methodology and device using digital audio. A security control device integrates physical intrusion detection functions, physical access control functions, and compressed, streaming, digital audio transmission capability. The device provides interfaces for a number of sensor inputs, including standard alarm monitoring sensors and audio sensors. The device is capable of communicating with a monitoring system over a variety of digital networking configurations options, including TCP/IP, via embedded Ethernet interface, or serial modem communications over telephone or digital cellular networks using PPP network protocol. The device may use backup channels of communications including telephone and cellular network communications. All communications with the device, whether to monitoring receiver or other local devices, may be secured with a minimum AES 128-bit encryption.