A method is provided that comprises tuning a radio system to a frequency band that contains a locally-broadcast terrestrial radio signal. The locally-broadcast terrestrial radio signal comprising a main signal component and a side data component is thereby received. In response to receiving the locally-broadcast terrestrial radio signal a determination is made as to a permissible time for processing the side data component using a time slot schedule. The side data component is processed at the permissible time. A message corresponding to the side data component is outputted to an output device. In some instances, the side data component includes the message. In other instances, the method further includes searching a message lookup list using a code included in the side data component. When a stored code is found that matches the code, the message corresponding to the matching stored code is outputted.