Techniques for performing system selection based on a usage model that uses “access strings”, “profiles”, and “activation strings” are described. Access strings are defined for wireless data services and provide a highly intuitive user interface. Each access string is associated with one or more profiles. Each profile includes various parameters needed to establish a specific data call. Each profile is further associated with an activation string that contains connection information for the data call. System selection is performed in two parts. In the first part, a wireless user views access strings for available data services, selects the access string for the desired data service, and returns the selected access string. In the second part, the wireless device selects a profile for a system most suited to provide the desired data service, from among all profiles associated with the selected access string.