Converging voice, video and data (triple-play) services onto a single network infrastructure is the current challenge facing the service provider (SP) industry including incumbent fixed-line operators, their challengers and mobile operators.
While this is undoubtedly a challenge, these next-generation networks (NGNs) also offer a number of opportunities for SPs to reduce operating expenditure and realise new revenue streams by introducing new services.
NGNs are defined as packet-based networks able to make use of multiple broadband, quality of service (QoS)-enabled transport technologies. In these networks, service-related functions are independent of underlying transport-related technologies. They offer unrestricted access by users to different service providers and support generalised mobility, which allows consistent and ubiquitous provision of services to users.
According to Peter Retief, regional chief executive of Business Connexion`s Africa region, one of the key problems facing SPs is the fact that many operators have legacy networks consisting of dual, separate voice and data networks.
"Although these networks may have proven reliability, the continued high operating costs and declining voice revenues from fixed-line and international calls inevitably affect the operators. This is why almost all of them are planning migrations from Time Division Multiplexing (TDM) infrastructure to NGN infrastructure," says Retief.
"SPs with an existing investment in legacy networks are often faced with the real dilemma of choosing when to start the migration to an NGN, and this dilemma is based on a number of factors."
Retief claims that these factors include the fact that voice revenue is declining and the existing investment in TDM infrastructure is not fully amortised. In addition, many vendors of traditional TDM voice switches are now focusing on NGN equipment.
"Despite these concerns, there are many reasons to accelerate the introduction of an NGN into the existing SP networks, including saving on operational expenses by consolidating multiple networks into a single multi-service entity, offering converged services of voice, video and data and the fact that NGNs are more flexible than TDMs."
Retief points out that once an SP has decided to migrate to an NGN, a choice must be made regarding the upgrade path to follow.
"There are three options available, the first of which is known as the forklift upgrade. This is where new NGN equipment is deployed to fully replace existing networks, and the cutover happens at a pre-planned time," he says.
"In practice, this option is very expensive and highly dangerous, and is seldom chosen as the upgrade path.
"The second option is the digital switch IP upgrade, where a central IP/MPLS network is built, and the surrounding Class 5 digital switches are connected to the IP network via add-on voice over IP (VOIP) modules."
However, says Retief, although this upgrade option may appear attractive, it is expensive and it limits the number of new services which can be offered to subscribers.
"The best option is the third and final one, notably the overlay solution, which sees the NGN deployed in parallel to the legacy TDM network. Existing Class 5 switches are gradually interfaced to the NGN via media gateways," he says.
"This approach is the recommended strategy for operators as it allows existing TDM equipment to be seamlessly integrated into the NGN, and for maximum return on investment on these assets to be achieved."
"It is also the safest approach, as legacy TDM networks continue to operate while the NGN links are tested and gradually introduced with little or no disruption to service."
The prime reason for most SPs to install NGNs is to be able to offer new services to clients and to generate new revenue streams. It is therefore crucial that they focus on key competencies while accelerating the availability of new services by allowing private sector partners to assist in the development.
"The list of potential new services is limited only by the imagination, but practical considerations will determine which services will be economically feasible in various markets," he says.
Retief believes there are lessons in this regard to be learned from the unexpected success of prepaid mobile telephony in Africa, so SP planners should not underestimate the demand for modern services in less developed regions, provided that the service meets the basic human needs.
"The migration from a TDM-based network to an IP-based NGN network is an inevitable step for all service providers, and I would recommend that SPs embark on this migration earlier rather than later."
"However, the most important factor to take into consideration when looking at migrating to an NGN is that it is done for business reasons and not just for the sake of having new technology," concludes Retief.
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