Operations support system
Operations support systems (also called operational support systems or OSS) are computer systems used by telecommunications service providers. The term OSS most frequently describes "network systems" dealing with the telecom network itself, supporting processes such as maintaining network inventory, provisioning services, configuring network components, and managing faults. The complementary term business support systems or BSS is a newer term and typically refers to “business systems” dealing with customers, supporting processes such as taking orders, processing bills, and collecting payments. The two systems together are often abbreviated OSS/BSS, BSS/OSS or simply B/OSS.
Different subdivisions of the BSS/OSS systems are made, depending on whether they follow the TM Forum's diagrams and terminology, industry research institutions or BSS/OSS vendors own view. Nevertheless in general, an OSS covers at least the application areas:
- Network management systems
- Service delivery
- Service fulfillment, including the network inventory, activation and provisioning
- Service assurance
- Customer care
History and development of OSS 
Before about 1970, many OSS activities were performed by manual administrative processes. However, it became obvious that much of this activity could be replaced by computers. In the next 5 years or so, the telephone companies created a number of computer systems (or software applications) which automated much of this activity. This was one of the driving factors for the development of the Unix operating system and the C programming language. The Bell System purchased their own product line of PDP 11 computers from Digital Equipment Corporation for a variety of OSS applications. OSS systems used in the Bell System include AMATPS, CSOBS, EADAS, RMAS, Switching Control Center System (SCCS), Service Evaluation System (SES), Trunks Integrated Record Keeping System (TIRKS), and many more. OSS systems from this era are described in the Bell System Technical Journal, Bell Labs Record, and Telcordia Technologies (now part of Ericsson) SR-2275.
Many OSS systems were initially not linked to each other and often required manual intervention. For example, consider the case where a customer wants to order a new telephone service. The ordering system would take the customer's details and details of their order, but would not be able to configure the telephone exchange directly — this would be done by a switch management system. Details of the new service would need to be transferred from the order handling system to the switch management system — and this would normally be done by a technician re-keying the details from one screen into another — a process often referred to as "swivel chair integration". This was clearly another source of inefficiency, so the focus for the next few years was on creating automated interfaces between the OSS applications — OSS integration. Cheap and simple OSS integration remains a major goal of most telecom companies.
A brief history of OSS architecture 
A lot of the work on OSS has been centered on defining its architecture. Put simply, there are four key elements of OSS:
- the sequence of events
- the information that is acted upon
- the components that implement processes to manage data
- how we implement the applications
- Business Management Level (BML)
- Service Management Level (SML)
- Network Management Level (NML)
- Element Management Level (EML)
(Note: a fifth level is mentioned at times being the elements themselves, though the standards speak of only four levels) This was a basis for later work. Network management was further defined by the ISO using the FCAPS model - Fault, Configuration, Accounting, Performance and Security. This basis was adopted by the ITU-T TMN standards as the Functional model for the technology base of the TMN standards M.3000 - M.3599 series. Although the FCAPS model was originally conceived and is applicable for an IT enterprise network, it was adopted for use in the public networks run by telecommunication service providers adhering to ITU-T TMN standards.
A big issue of network and service management is the ability to manage and control the network elements of the access and core networks. Historically, many efforts have been spent in standardization fora (ITU-T, 3GPP) in order to define standard protocol for network management, but with no success and practical results. On the other hand IETF SNMP protocol (Simple Network Management Protocol) has become the de facto standard for internet and telco management, at the EML-NML communication level.
From 2000 and beyond, with the growth of the new broadband and VoIP services, the management of home networks is also entering the scope of OSS and network management. DSL Forum TR-069 specification has defined the CPE WAN Management Protocol (CWMP), suitable for managing home networks devices and terminals at the EML-NML interface.
TM Forum (formerly the TeleManagement Forum) 
||This section may be too technical for most readers to understand. (September 2008)|
TM Forum is an international membership organization of communications service providers and suppliers to the communications industry. While OSS is generally dominated by proprietary and custom technologies, TM Forum is regarded as the most authoritative source for standards and frameworks in OSS. TM Forum has been active in proving a framework and discussion forum for advancements in OSS and BSS.
By 2005, recent developments in OSS architecture were the results of the TM Forum's New Generation Operations Systems and Software (NGOSS) program, which was established in 2000. This established a set of principles that OSS integration should adopt, along with a set of models that provide standardized approaches.
NGOSS models 
- An information model (the Shared Information/Data model, or SID) - now more commonly referred to as the Information Framework,
- A process model (the enhanced Telecom Operation Map, or eTOM) - now more commonly known as the Business Process Framework,
- An application model (the Telecom Applications Map) - now known as the Application Framework, an architecture (the Technology Neutral Architecture) and a lifecycle model.
NGOSS architectural standards 
The TM Forum describes NGOSS as an architecture that is:
- "loosely coupled"
- component based
The behavior can be controlled through the use of process management and/or policy management to orchestrate the functionality provided by the services offered by the components.
The early focus of the TM Forum's NGOSS work was on building reference models to support a business stakeholder view on process, information and application interaction. Running in parallel were activities that supported an implementation stakeholder view on interface specifications to provide access to OSS capability (primarily MTNM). The MTNM work evolved into a set of Web Services providing Multi-Technology Operations System Interfaces MTOSI. Most recently, the OSS through Java initiative (OSS/J)  joined the TMF to provide NGOSS-based BSS/OSS APIs.
Future work 
Considerable work remains, primarily in building out the system stakeholder reference models, which are needed to support a business process driven and SOA styled approach to using model driven development for specifying the additional implementation stakeholder interface specs (for SOA Web Services, EJB and EAI). These are required to meet the demands of Service Providers operating using the IMS architectural framework and NGN communications networks.
See also 
- COSMOS (Telecommunications)
- Loop Maintenance Operations System
- Service Evaluation System
- Switching Control Center System