in OPEX with usage of more OSS solutions from different vendors, reduced interoperability between OSS solutions, and lack of flexibility in bringing in new OSS function- ality. The first popular attempt to define the management stack that was widely accepted was the TMN (telecommunications management network) model. The TMN model divided the management stack into five layers. The layers are: business management layer (BML), service management layer (SML), network management layer (NML), element management layer (EML), and the network element (NE) layer. There are management agents running on the network ele- ments in the network element layer that collect management data. This informa- tion from agents is collected by the element managers in EML. In a network with multiple network elements, there will be multiple element managers. To provide management data at a network level by aggregating information of multiple net- work elements in the network, a network manager is used that sits in NML. Over the network infrastructure, there can be multiple services that will be hosted. The management of the service happens in the SML. Finally the upper most layer of TMN, the BML is to handle business data in service provider space. The BML takes feed from the SML and it is the service reports that are used as input in the generation of billing reports and invoicing at BML. The TMN from ITU-T provided a means to layer the management stack and also helped in defining the basics management blocks using FCAPS (fault, configu- ration, accounting, performance, and security). It still was not elaborate enough to map the various telecom processes into the management layers. So TMF expanded the TMN layers to form a new model called telecommunications operations map (TOM model). This model brought in more granularities in defining processes in service and the network layer and added modules related to customer interface and customer care process. TOM was later expanded from just an operations manage- ment framework to a complete serv