A system (6) arranged to route a dialog between an operator of a call center and a customer. Said system comprising a communication script (44) arranged to follow a scenario corresponding to a customer's case by means of presenting a plurality of messages to the operator. Said system further comprising means (3,7) for determining a type of the scenario, means (11) for determining a current state of the scenario and a generator (9) of the communication script (44). Said generator being arranged to select a plurality of messages (44a, 44b, 44c) from a database of messages (10) in compliance with said type and said current state in order to obtain a plurality of selected messages. Ranking means (14b) are arranged to rank the selected messages, wherein the message with a higher relevance to the current state of the scenario being ranked higher. A user interface (8) arranged to present the selected messages together with their rank (46a, 46b, 46c) to the operator in a list (18).