Abstract: A method and system that enables a subscriber and/or operator to specify one or more conditions under which a given feature such as a supplementary service (SS) is to be executed. When a call event occurs, the relevant telecommunications network evaluates a logical expression that includes variables corresponding to the specified conditions. If (i) the specified conditions are such that the logical expression for the given feature is “TRUE” and (ii) the feature is “ON”, then the network executes the given feature and may further perform a specified task related to the executed feature. If (i) the logical expression is not evaluated to “TRUE” or (ii) the feature is not “ON”, then the network does not execute the given feature. The network preferably evaluates a logical expression at least for each feature that the subscriber has turned “ON”.