A method in a telecommunications system, in which there are at least three parties involved in the system's exploitation, namely at least one service provider capable of providing services for at least one user, and at least one operator responsible for the operation of the telecommunications system, wherein payable services delivered to an authorized and authenticated user are identified, and in which system each service transaction as well as the user are identified. The definition of the transaction flow is done on the basis of at least one predefined transaction rule and the parties involved are allowed to dynamically alter the function of at least one of the rules and/or the execution order of multiple rules for creating a flexible transaction flow.