The RDFS is a public service provide by ACMA for the safety of people in remote area the RDFS do not use Sellcal as much as other networks and do not provide telephone or skids on their base stations, they are emergency only network, To use the RDFS system you must apply to ACMA for a Licence to operate on the network, failure to do so is an offence. Each user is given a call sign in the form of a VZXNNN (X is a letter and N a number 0-9) number that indentifies them on the net work.