Patent ID: 8892747

Claim:
A communication system comprising: a communication service client terminal to generate: a first one or more messages that contain at least one first criterion that is respectively met or not met by each of a plurality of further communication service client terminals, and after reception of an identifier for a group including one or ore of the further communication service client terminals that meet the at least one first criterion, a second one or more messages that contain at least one second criterion, different from the at least one first criterion, that is respectively met or not met by each of the plurality of further communication service client terminals, the second one or more messages further containing a request for provision of a communication service and a specification that the further communication service client terminals that meet the at least one first criterion and the at least one second criterion can be participants in the communication service provided; and a server computer configured to: generate, in response to the first one or more messages, the identifier for the group including the one or more of the further communication service client terminals that meet the at least one first criterion, and dynamically generate, in response to the second one or more messages and during an establishment of a communication session of the communication service between the communication service client terminal and the further communication service client terminals that meet the at least one first criterion and the at least one second criterion or during a running communication session of the provided communication service between the communication service client terminal and the further communication service client terminals that meet the at least one first criterion and the at least one second criterion, information describing the further communication service client terminals that meet the at least one first criterion and the at least one second criterion and can be participants in the communication session of the communication service provided, check, in the course of providing the communication session of the communication service, the validity of the information, and update the information in response to changes in the further communication service client terminals that meet the at least one first criterion and the at least second criterion; wherein a communication service server computer is to provide the communication session of the communication service between the communication service client terminal and the further communication service client terminals that meet the at least one first criterion and the at least one second criterion as participants on the basis of the information, and to alter the participants in the communication session of the communication service provided on the basis of the updated information.