The present invention relates to a method for collecting inter-operator charging information in a group communications system comprising a first group communications network element and a second group communications network element. An intermediate charging information collection unit is provided in an interface between the group communication network elements. The charging information collection unit examines a group communications message received from the first group communications network element or the second group communications network elements. A charging information unit is generated based on at least a portion of the message and the charging information unit is applied for inter-network charging to charge for use of inter-network resources.