In a policy and charging control method carried out by a server including a policy and charging enforcement function (PCEF), identification information for identifying a particular service instance of a particular service type is obtained. When a packet is received, the PCEF determines whether the packet belongs to the particular service instance by using the identification information and by inspection of at least one of Open Systems Interconnection (OSI) layer n control information of the packet, wherein n is an integer equal to or larger than 3, and the packet's payload. If it is determined that the packet belongs to the particular service instance, the PCEF updates a usage parameter representing an accumulated usage associated with the particular service instance. The PCEF then makes available to a policy and charging rules function (PCRF), the usage parameter or information derived therefrom.