A method and apparatus for assessing the compatibility of a selected network feature with the network features of an existing telecommunications network 10 comprises providing an abstraction of each network feature in the form of a data model 100 which defines the relationships between any network elements 12 or nodes 27, software elements 13 and software features 14 required for each network feature. Information 19 is then collected about the existing telecommunications network 10 to identity the deployment of the network features in the existing network. This information is then combined with the data model 100 to build a feature compatibility matrix 107 which defines the compatibility of network features in the existing telecommunications network 10. The matrix 107 can then be interrogated with information defining the parameters of the selected feature to be added or upgraded to determine whether the selected feature is compatible with features of the existing network.