Patent ID: 7664490

Claim:
A method for establishing a call in a communication system including an Instant Messaging (IM) application provided by a Session Initiated Protocol (SIP) server connected to a number of IM clients, each associated with at least one conference endpoint managed by one or more management systems at least adapted to schedule and/or investigate possibilities for a conference between two or more individuals, comprising: transmitting a first SIP invite message from an inviting IM client to the SIP server including a Global Unique Identifier (GUID), a first SIP Uniform Resource Identifier (URI) identifying said inviting IM client and a second SIP URI identifying an invited IM client; upon reception of said first SIP invite message in the SIP server, investigating in the management system whether the respectively associated endpoint of said inviting IM client and said invited IM client satisfy a predetermined set of conditions, at least including whether the respective associated endpoints are idle; if said set of conditions are satisfied, transmitting a second SIP invite message from the SIP server to said invited IM client; and if said second SIP invite message is accepted by said invited IM client, returning a SIP invite accept message to the SIP server and instructing the management system to set up a call between the respectively associated endpoint of said inviting IM client and said invited client.