For IMS to really take off, solid OSS structures which underpin the technology are imperative, as David Sharpley explains

The concept of converged networks and services is becoming a reality as IP Multimedia Subsystem (IMS) technology gains attention and acceptance in the communications industry. With IMS, service providers can enable their customers to mix multimedia service components – text, pictures, voice and video – over a single connection. IMS provides the Internet Protocol (IP) multimedia and telephony core network that supports IP-to-IP sessions over both wireline and mobile networks. Additionally, IMS includes session control, connection control and an application services framework along with subscriber and services data. 
Ultimately, IMS has the potential to create a fluid environment where users can combine and recombine existing individual services in real-time. And it will enable service providers to generate new revenues by quickly and economically moving through the service creating and deployment lifecycles.
To take full advantage of this new revenue opportunity, service providers must either enhance their existing Operations Support System (OSS) solutions, or introduce new systems. Effective support for IMS requires new OSS capabilities, configuration approaches and integration mechanisms. The OSS stack must provide:
• Unprecedented simplification and abstraction of services and the network;
• Simplified support for the underlying network infrastructure, which changes as IMS is deployed;
• A flexible Service Delivery Platform (SDP)to support rapid service creation lifecycles and reduced time to market; and
• Increased capabilities for managing service profiles and subscriptions directly into the application layer.
With a common Session Initiation Protocol (SIP) and MultiProtocol Label Switching (MPLS)-based core network, various access technologies can be enabled with the same control plan intelligence. Moreover, service providers can deliver seamless access to the same services residing in the application layer.  Session handling, service orchestration and processing are kept in the higher layers. By doing so, they are decoupled from the network equipment. This architecture allows service providers to exchange one network access format for another and to switch between the formats on the fly with uninterrupted session handoff. 
The functionality of IMS makes it a key enabler for Fixed Mobile Convergence (FMC) by blurring the lines between the historically separate worlds of wireless and wireline services. FMC ultimately leads to a seamless, unified offering that intelligently hops between fixed and mobile networks to offer the best service and reception possible, with the most efficient use of network resources available.

IMS OSS challenges
While the benefits of IMS are obvious, there also are a number of challenges. These challenges include interoperability, availability of complete solutions and a clear business case for the technology. As a result, service providers may be quick to endorse IMS in theory, but are cautious in their implementation plans.
New IMS deployments must interwork with existing circuit-switched and packet-switched networks. IMS is also driving new requirements in the OSS arena. In fact, well-adapted OSS systems will become essential to help unlock the value in IMS, as service fulfilment and management requirements become more dynamic and sophisticated.

Plug & play support
As IMS becomes more widespread, new equipment will be needed. Traditional vendors are reworking their products, while new entrants focused solely on IMS products are entering the market. The result: a proliferation of devices from multiple vendors that may not offer complete functionality. In this environment, interoperability becomes a key concern.
To keep up the pace with these equipment changes from an OSS perspective, service providers must be able to easily drop in new device drivers for each piece of IMS equipment they select. Similarly, the provisioning logic for each new service must be easily managed as its own entity, without affecting other services and must provide abstraction from the network in much the same way IMS abstracts control and application services from the network. The technical ability to provision, model and collect billing records from these devices is crucial to the deployment of revenue-generating, commercial IMS-based service offerings.

Simultaneous support
OSS functionality for next-generation IMS services should coexist with the OSS for mature existing services. Underlying OSS platforms should be consistent in design, operational and architectural consistency, which will allow for an easy transition into a high-volume and fully automated production environment when the business conditions allow. Plug and play service and network OSS components must be well defined and partitioned from one another to allow easy revisions to individual configurations without affecting other deployed capabilities. Furthermore, rather than only permitting coexistence, OSS abstraction must facilitate migration of legacy service implementations to the next-generation network with little, or no impact, to the network operator's front office or to the end user.

Time-to-market needs
IMS is expected to spawn the introduction and proliferation of innovative new services. In such a dynamic market environment, service providers need an OSS that gives them the agility and control to define, deploy and refine new IMS services quickly and at low cost. Ultimately, this flexibility must be combined with the scalability and robustness of an OSS solution that can scale to handle high-volume, mass-market services that are anticipated for the future.

The OSS must support the entire service lifecycle – from service incubation to product maturity. Service creation includes not only defining the service itself, but also defining the OSS stack behaviour for fulfilment of new service requests. OSS capabilities must interface with the  IMS network architecture layers at run time, as well as the SDP environment at design time. Existing services configured in the network should be exposed to the SDP for re-use and re-assembly, in the manner of a Service Oriented Architecture (SOA). Similarly, SDP tools should have the ability to reach into OSS design-time tools for reconfiguration and new service deployment.
OSS applications will need to address the changing requirements driven by IMS in the control, policy and application planes of next-generation network architectures. In this scenario, more focus is placed on service definitions and profiles, service subscriptions and application layer service provisioning. Physical and logical inventory expands to service inventory and service capability management. Network provisioning and activation broadens to service profile management, subscriptions updates and instantiating application layer services for customer consumption. Billing becomes more customer- and service-oriented, requiring new ways to process usage records in order to achieve desired pricing models.

Policy and control
The intelligent control and policy functions built into the IMS network will create a more fluid environment where service behaviour decisions can be made instantaneously.  As a result, OSS solutions will be more tightly integrated into the network because it plays a critical role in service delivery. This shift will raise the bar for OSS reliability, availability and performance. Standards-based, open APIs working into a SOA are critical for achieving the OSS interoperability, flexibility, reusability and time-to-market capabilities needed for the IMS environment.
The success of IMS hinges on the ability of service providers to attain business value from its deployment. Service provider must capture the revenue stream from the service innovation promised by IMS, while customers will require flexible pricing schemes. Billing systems capable of charging subscribers for new services in unique ways will be supported by enhanced charging mediation capabilities with advanced functionality not present in legacy applications.
IMS-based services require a mix of session, event and subscription-based service pricing, including revenue sharing with partners. Billing for service and network usage means collecting and processing usage information from a heterogeneous mix of network elements at multiple layers in the network.

IP domain capabilities
IP forms the foundation of the IMS network. Effective OSS platforms must, therefore, feature strong domain capabilities for these requirements. OSS systems with insufficient IP capabilities will not be viable in an IMS-based world. Rich out-of-the-box service support for key enablers, including MPLS IP Virtual Private Networks (VPN) in Layer 2 and Layer 3 and IP Quality of Service (QoS) using policy-based networking techniques, are key to establishing the connectivity and network-level services at the core of the IMS network. The IP OSS should provide a combination of abstracted, multi-vendor IP service activation, along with discovery, configuration management and integration with service assurance tools.
 Today, service providers must consider a single, comprehensive service provisioning platform that can be leveraged in the long-term as IMS evolves. An effective OSS for both existing and next-generation services must offer a full range of provisioning and activation capabilities. These capabilities range from the traditional tasks of setting up the network infrastructure and connections, to the provisioning of service subscriptions, high-volume real-time customer service profile updates and application layer services. This type of flexible OSS platform provides both the horizontal scope of interfacing with virtually any type of network equipment and the vertical scope to seamlessly bridge all three layers of the IMS architecture.                               

David Sharpley is Executive Vice-President of Marketing for MetaSolv Software, Inc.

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