A security monitoring system for a building or a secured space within a building, the system being operatively connected to a monitoring station , the system including: a control unit for controlling, arming and disarming the security monitoring system , and having a first radio frequency transceiver which can support a first maximum bitrate, and a second radio frequency transceiver which can support a second maximum bitrate lower than the first bitrate, and a controller for controlling the radio frequency transceivers ; a camera node having a node controller ; an image sensor for capturing images; a primary node radio frequency transceiver , for communication with the control unit ; a secondary node radio frequency transceiver , to receive control messages from the control unit , the primary node radio frequency transceiver supporting a higher maximum bitrate than the secondary node radio frequency transceiver ; the node controller of the camera node being configured to: transmit a captured image with a first image ID both as a first image file using the primary node radio frequency transceiver and as a second image file using the secondary node radio frequency transceiver , the first image file having a higher resolution and a larger size than the second image file; the control unit being configured, on reception of the first to arrive of the first or second image files, to transmit the first arrived file to the monitoring station , and thereafter, if the first arrived file was the second image file, on arrival of the first image file, to transmit the first image file to the monitoring station . a control unit for controlling, arming and disarming the security monitoring system , and having a first radio frequency transceiver which can support a first maximum bitrate, and a second radio frequency transceiver which can support a second maximum bitrate lower than the first bitrate, and a controller for controlling the radio frequency transceivers ; a camera node having a node controller ; an image sensor for capturing images; a primary node radio frequency transceiver , for communication with the control unit ; a secondary node radio frequency transceiver , to receive control messages from the control unit , the primary node radio frequency transceiver supporting a higher maximum bitrate than the secondary node radio frequency transceiver ; the node controller of the camera node being configured to: transmit a captured image with a first image ID both as a first image file using the primary node radio frequency transceiver and as a second image file using the secondary node radio frequency transceiver , the first image file having a higher resolution and a larger size than the second image file; the control unit being configured, on reception of the first to arrive of the first or second image files, to transmit the first arrived file to the monitoring station , and thereafter, if the first arrived file was the second image file, on arrival of the first image file, to transmit the first image file to the monitoring station . transmit a captured image with a first image ID both as a first image file using the primary node radio frequency transceiver and as a second image file using the secondary node radio frequency transceiver , the first image file having a higher resolution and a larger size than the second image file; the control unit being configured, on reception of the first to arrive of the first or second image files, to transmit the first arrived file to the monitoring station , and thereafter, if the first arrived file was the second image file, on arrival of the first image file, to transmit the first image file to the monitoring station . <EOS>