and open source development of product. 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 TeleManag