1. A method of monitoring a plurality of monitorees, said method comprising steps of: retaining, at a field node, wherein said monitorees and said field node are remotely located relative to a control facility, data identifying unique codes for said monitorees; associating a transmitter with each of said monitorees; from each of said transmitters, repetitively transmitting one of said unique codes from time to time in accordance with a predetermined schedule; receiving at least a portion of said transmitted codes at said field node; activating an alarm at said field node when one of said unique codes has not been received in accordance with said predetermined schedule, sending a field report message from said field node to said control facility after said activation step; and refraining from sending said field report message until a predetermined duration has transpired after said activation step.