An apparatus and method control transmission of messages over a fixed bandwidth link from fixed position communication devices to a central controller in a load management system. The messages include information relating to electric power consumption by power consuming devices located at service points that include the communication devices. In one embodiment, the central controller determines an identifier associated with each communication device, a reporting period during which the messages are to be transmitted by the communication devices, and transmission increments within the reporting period. The controller allocates each transmission increment to a respective group of communication devices. The controller then determines a transmission time for a message from a particular communication device based on the identifier for the particular device, a duration of a transmission increment allocated to a group of communication devices that includes the particular device, and a quantity of communication devices in the particular device's group.