More competition leading to more challenging services that work on the specified interface. d. Generalized NMS functions: This corresponds to modules with generic net- work management functionalities independent of the network being handled. There are a set of functions that has to be done by an NMS with all kinds of telecom networks whether it is GSM, CDMA, or IMS. Some of these functions are a correlation of fault and performance data, user management, administration, and security. e. Specialized NMS functions: These are functional modules specific to a net- work like HSS subscriber provisioning in an IMS network, a charging model for UMTS, and SO on. Use of the SOA architecture ensures that the mod- ules in specialized NMS are self-sufficient and does not affect the working of generic NMS. The addition of specialized functionalities is done only in phase 3 of devel- oping the NGNM solution. Phase 1 of NGNM is limited to the development of a generic NGNM framework. f. External applications: These are applications that interact with the NMS. It can be an EMS, GUI, OSS, or even a network element that has an agent that can respond to queries from an NMS. Advantages of having a generalized NMS functions set and isolating it from a specialized set: Generalized functions can be reused across different set of networks and isolating it from the specialized set reduces effort to testing both when a specialized function is added and when the generalized function is put to support a new network. The specialized functions can be provided as an add-on or plug-ins for a solution suite that comprises of generalized functionalities leading to bet- ter revenue and customized NMS. Fundamentals of EMS, NMS and OSS/BSS 34.5.2 Generic Functionalities for NGNM The phase 2 of NGNM solution is adding the NGNM functionalities. The com- pany that goes about implementing the NGNM solution has the liberty to choose the set of NGNM functions to be added in the product. The document TR133 of TeleManagement Forum (TMF) can be referred to und