Patent ID: 8244816

Claim:
A method for use in a communication system implemented over a network comprising a plurality of user nodes, the method comprising: at each of the user nodes associating a respective presence status indicating an availability of said each of the user nodes for communication within the communication system; at each of a first transmitting one or more of the user nodes, determining addresses for each of a plurality of others of said user nodes; using the determined addresses, transmitting, by the first transmitting user node, repeated presence messages to said each of the plurality of others of said user nodes, each of the presence messages comprising at least one of a request for presence status of the other user nodes, and a notification of presence status of the first transmitting user node; determining a measure of resource usage in relation to the first transmitting user node which carries out said transmitting step; and controlling a regularity of said repeated transmission of presence messages in dependence on the determined measure of resource usage of the first transmitting user node which carries out said transmitting step, such that the repeated transmission of presence messages is dependent on the determined measure of resource usage of the first transmitting user node.