Method of rekeying roaming communication units

In a communication system including a home key unit with an associated home coverage area, a first key unit with an associated first coverage area, a second key unit with an associated second coverage area, and including a communication unit that may roam from the home coverage area to the first coverage area or the second coverage area, a method for over-the-air rekeying of the roaming communication unit as it roams from the home coverage area, the method comprising the steps of:

• a) after entering the first coverage area, transmitting, by the roaming communication unit, a key request to the first key unit, wherein the key request includes a communication unit identification code for the roaming communication unit, a home identification code, and a request for a key;
• b) transmitting, by the first key unit, a unit information request to the home key unit, wherein the home key unit is affiliated with a system identified by the home identification code, the unit information request including the communication unit identification code, the home key unit identification code, and the request for a key;
• c) transmitting, by the home key unit, a rekeying information packet to the first key unit;
• and
• d) transmitting, by the first key unit, a key information packet to the roaming communication unit.