In the current competitive world@ Quality of Service (QoS) is becoming@ jointly with cost@ a key parameter in selling and buying telecommunications services. At the same time@ technology and liberalization trends are raising new types of concerns unknown with the Plain Old Telephony Services (POTS) using switched connections provided by a single monopoly supplier. Nowadays@ there are several standards describing QoS measurements but the questions of which indicators are to be monitored and which values they should meet are still open. The present document proposes a methodology for the identification of parameters relevant to the users that can be used either to monitor the QoS of Telecom services used by the private customers or for a Service Level Agreement (SLA) between a customer and a supplier of Telecommunications services as that proposed in EG 202 009-3 [5]. It gives guidelines on how to obtain user's QoS requirements@ prioritize the criteria or parameters@ establish a preferred value for each of these parameters@ while EG 202 009-2 [4] proposes service specific QoS parameters.