Patent ID: 7844667

Claim:
A presence system, comprising: a presence service client means for providing presence information of a first presentity and for receiving presence information of at least one second presentity; a presence service means for receiving presence information of the first presentity from the presence service client means and for delivering presence information of the at least one second presentity to the presence service client means; and a presence calculating means for determining the presence information of said first presentity based on a change in the presence information of the at least one second presentity, wherein said presence calculating means includes a presence change rule storing means for storing a presence change rule that prescribes how the presence information for said first presentity is determined based on the presence information of said at least one second presentity, wherein said presence change rule comprises a conditional expression for the presence value of said at least one second presentity and a change of value for the presence information of the first presentity in which the change in value is applied if the conditional expression is satisfied.