As technologies for carrying voice and data mature and converge, service providers and enterprises are increasingly viewing voice over packet (VoP) based network as a way to reduce communications costs, boost end-user productivity and enable new applications. Such network architectures not only handle multiple kinds of traffic in a cost-effective way but also competitive services, which integrate voice, data and multimedia, which are going to be the key differentiators.

Operators’ Strategy

When considering the deployment of NGNs, strategy of a telecom operator is going to depend upon its history (incumbent vs green field), market situation (deregulated vs monopolistic, strength of competitors), status of its networks (single equipment provider vs several, recent or less recent products), and the evolution of its customers’ needs (traffic, services, etc).

For the operator, some of the key reasons in favor of NGNs are to:

l reduce time to market for new technologies and services
l facilitate vendor, carrier, or third-party development of software
l reduce operational complexity by standardized modular systems
l separate call processing from switching/transport function through open interfaces

The associated objectives underlying this approach would include:

l support ATM and IP connections in addition to legacy TDM connections
l keep the present level of voice features when evolving from TDM-based networks to VoP solution
l support voice, video and data services

To address these needs, the vendors are developing NGN solutions (including call servers/softswitches, trunking and access gateways, IP/ATM networks nodes, etc) to cope with the actual requirements of different operators, and are offering traditional voice services as well as advanced new multimedia services.

The new operators may directly install softswitches and gateways (trunking or access gateways) to handle the Class 4 or Class 5 applications. However, Class 5 application on softswitches will take some time to develop. So they look for platforms, which can provide Class 5 applications on TDM at present, but which can migrate to NGN smoothly.

Large installed base of TDM-based traditional networks, make the incumbent operators look for a smooth transition to the full NGN architecture, to protect the large investments already made in the access nodes. Hence, they look for hybrid-platforms, which can give all the features of TDM and evolve to a softswitch—integrated inside the TDM switch itself—ensuring migration of subscribers from the TDM environment to the NGN environment, without any discontinuity.

Platforms being designed for these large incumbent operators address the following requirements:

n investment protection by reuse of the installed switches as well as external devices, such as IN service control points, network management centers or customer-care and billing systems
n networks’ smooth evolution without service disruption
n functional continuity of features and services

NGN Network Strategy
Existing networks, catering to separate voice and data transports, can be optimized by the introduction of new high-capacity switches to drastically reduce the number of switches and thus, the OPEX costs.

At access level, voice and data convergence is already happening through mass deployment of ADSL on copper lines. At the transit level, NGN is implemented initially via VoP transport with stand-alone call servers (Class 4 or transit call servers), controlling trunking gateways in charge of the PSTN-to-packet adaptation.

Introduction of the media gateway controller (MGC) feature in TDM switch, enables the operators to move smoothly to NGN with full continuity of services at the desired deployment pace. MGC allows control of additional gateways, which interconnect existing access unit/trunk to packet network.

This solution allows a progressive hand-over of voice traffic from the TDM world to the data world, while retaining the existing end-user services as well as the control and management interfaces. This would ensure networks’ smooth evolution without service disruption, besides investment protection. n