Patent ID: 7379732

Claim:
A method of instant messaging between a plurality of messaging clients configured to transmit instant messages and presence data between each other, the presence data including a first known state in which a messaging client is receptive to communicating with other messaging clients, comprising: receiving communications including presence data from each of the messaging clients at a presence server, the presence server determining the present state of the messaging clients using the presence data and storing information in a state table entry for each of the messaging clients indicating the present state of the messaging client; for each of the messaging clients that is in the first known state, the presence server periodically transmitting to each of the messaging clients present state data regarding the other messaging clients stored in the state table entries; when the presence server does not receive any communications from a messaging client during a predetermined period of time, then modifying the state table entry for the non-communicative messaging client to be an unknown state indicating that the presence server cannot determine the present state of the messaging client, and thereafter inhibiting further periodic transmissions of the present state data regarding the other messaging clients until the presence server observes the state of the messaging client by receiving presence data from the messaging client, without transmitting any presence information requests from the presence server to the messaging client, indicating that the messaging client has returned to the first known state.