Virtualized PoP: the way of the future for wholesale carriers

Hot Telecom on behalf of Metaswitch Networks
02 Dec 2015

In today’s environment, international wholesale voice networks are normally comprised of two core sets of equipment needed to handle customer interconnections:

  1. Voice switches with TDM interfaces to handle the remaining interconnects with carriers yet to migrate to IP
  2. Session border controllers (SBCs) able to interconnect, in a secure way, service providers ready for VoIP.

Supporting those key elements are all the ancillary pieces of equipment supporting C7 signaling, transcoding, conversion between TDM and VoIP, routing control plus all the Operations and Maintenance (O&M) systems required to manage the network.

Today, all this equipment requires its own controlled environment, which forces wholesale carriers to often have a relatively static and cumbersome hierarchical network structure, with equipment replicated at most of the PoPs in the network hierarchy as follows:

  • Core: A network backbone formed of core PoPs and providing interconnects to most of their carrier partners.
  • Access: Regional or local PoPs connecting to customers and suppliers in different parts of the world.

See Also

Telecom Asia e-Brief: NFV


All of this comes at a significant cost, both for initial capital and ongoing operations. It also makes it very difficult to reduce costs, as each component has a logical reason for being in place and many of the costs appear to be inescapable without seriously threatening the reliability of the services.

To compound these issues, even if there is a clear drive in the industry towards a more flexible VoIP interconnect model, all the remaining TDM components in today’s networks remain very inelastic in terms of their operational cost. A TDM switch requires full power, space, technical support and spares holding regardless of the traffic it is supporting. And the final customer on that switch will therefore be massively unprofitable as a result.

But the world is changing, and some SBC vendors have been leaders in the virtualization of these functions, enabling the SBC to operate on a cloud-based virtualized computer environment and resolving some of the cost and flexibility issues that carriers are contending with.

This virtualization of key network functions opens up the potential for the use of virtualized PoPs to bring in a significantly different approach to network deployment, one which directly ties much lower costs to the changing usage patterns.

Service providers increasingly expect to connect to a wholesaler in their own country if possible, but at a minimum within the region. This is partly driven by the cost of bandwidth, especially if a private IP connection is used for that interconnect circuit, but it is also driven by quality concerns.

While it is technically possible to build a network with one massive global PoP and switch all calls via that node to achieve the maximum cost efficiencies, this rarely works in practice, as it seriously hinders voice call quality. To bring the audio back to a central point, and then routing it via the chosen partner carrier on to the destination, adds significant latency to every packet carrying the conversation, making that call difficult to understand and almost ensuring low end-user satisfaction. Often this results in a much shorter call duration than expected, which has a direct impact on revenue. So this theoretically inexpensive network deployment of a single global PoP ultimately results in much less business for the carrier.

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