Abstract Over the past few years, the subject of Intelligent Network (IN) has captured the interest of the telecommunications community. The objective of IN is to allow the introduction of new capabilities in the telecommunications network and to facilitate and accelerate in a cost-effective manner, service implementation and provisioning, in a multivendor environment. However, this objective confronts a major obstacle known as the feature interaction problem. The feature interaction problem occurs when a feature is prevented from performing its functionalities in the presence of other features. In the first part of the thesis, we describe a LOTOS model for structuring the Functional Entities (FEs) that are defined in the Distributed Functional Plane (DFP) of the CS1 IN Conceptual Model (INCM), and that are involved in the establishment of a call/connection and invocation and processing of services. The specification of IN services is achieved using Service Independent building Blocks (SIBs). It is designed in a way that independent specification and rapid introduction of services is provided. In the second part of the thesis, a method for detecting feature interactions between services is developed. The method is limited to the detection of interactions caused by violation of features properties. It is based on formalization of feature's properties, derivation of goals satisfying the negation of these properties and use of Goal Oriented Execution to detect traces satisfying these goals. A trace satisfying a goal shows that an interaction exists between the specified features by describing a scenario violating one of the properties of the introduced features. It is concluded that LOTOS is useful as a Formal Description Technique (FDT) in the Service Creation Environment (SCE). The developed specification can be used for adding specifications of new services, and for detecting interactions caused by violation of properties, if there are any.