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September 1, 2004

5 Min Read
Living with Legacy

The transformation of traditional voice

networks to next-generation networks has been taking place in various forms since the mid-1990s. When we think next-generation, we typically envision a transition from circuitswitched to packet-switched technologies, or from a legacy TDM network to an all- VoIP network.

Today, nobody would doubt the VoIP evolution will continue and, ultimately, we will have a single packet-switched telephony network supporting voice and data, multiple applications and high quality of service levels.

But, what progress has been made so far in transitioning service provider networks? And what should the road map look like over the next few years?

Tier 1 carriers account for the majority of next-gen network investment with the cable companies and IXCs being the most active in North America. The vast majority of carriers have implemented selected VoIP technologies and large-scale deployments are expected to begin in the coming years.

In new numbers released this summer, Gartner Dataquest estimates total next-gen network infrastructure vendor revenue worldwide to total $13.1 billion in 2004, $15.5 billion in 2005 and $18.0 billion in 2006. Comparatively, TDM infrastructure vendor revenue worldwide has been declining, from approximately $22 billion in 2001 to an estimated $7 billion in 2006.

Although the implementation of nextgen strategies is moving forward at a steady pace, the speed of universal deployment will be dependent upon existing network infrastructures.

Some startup telcos successfully have deployed all-IP networks in developing markets where an established base of circuit switches does not exist. However, to expand geographically, these service providers will have to work with established networks for at least the next few years. In the near-term, a limited amount of voice traffic will be IP end-to-end.

With legacy equipment still dominating voice networks, VoIP solutions are commonly deployed in hybrid situations - or within networks using both circuit- and packet-switched technologies. Current VoIP implementations typically include one of these scenarios:

  1. VoIP gateways are added within a network’s access layer.

  2. VoIP functionality is added to Class 4 switches and the signaling, billing and network management applications.

  3. Class 5 VoIP switches are integrated or colocated at Central Offices.

Many existing carriers have deployed VoIP solutions; however, few have replaced their entire legacy networks with VoIP technologies.

The recent telephony market meltdown has pressured many carriers into finding ways to maximize the return on their existing network infrastructures. As a result, today’s established carriers are reluctant to use their limited capital expenditure dollars to develop an entirely packet-switched network, even though VoIP requires less network infrastructure and offers plenty of benefits.

This does not mean service providers should not have a road map for migrating completely to a next-gen network. Clearly, service providers not currently deploying or planning to deploy VoIP solutions universally over the next few years have put their future viability at risk.

Several priorities form the basis of a sound next-gen strategy and road map:

  • More important than the underlying technology, a next-gen network must be aligned with the communication needs of enterprise customers and consumers.

  • Next-gen networks must have some important attributes, including the ability to handle different types of content seamlessly, be transparent to users, change and grow through modular components, adapt to changing environments, and provide security.

  • Service providers need to understand where they can streamline operations and management by flattening the network architecture. They will also need to evaluate how next-gen technology will facilitate and simplify the delivery of new services.

  • A consistent goal for next-gen networks is to unify critical applications such as back office, billing and network management.

  • Next-gen technology must be able to operate across multiple network platforms and protocols.


Whether a service provider has an all VoIP network, all circuit-switched, or a combination of the two, most applications will require VoIP components to talk to legacy equipment for several years to come. Therefore, a crucial step in the migration strategy is to enable crossnetwork communication.

Service providers must have a methodical plan to interconnect disparate networks and simplify their overall network infrastructure.

In addition, they must migrate to a single network management system. These beginning steps will help carriers reduce operating expenses, identify redundant network elements and extend the reach of their network coverage.

When networks have been merged and integrated successfully, service providers can begin to deploy value added VoIP services.

These applications can provide new revenue streams and differentiated offerings.

To help carriers migrate more easily, equipment vendors are offering VoIP products specifically designed to work alongside existing TDM networks. Carriers can begin a VoIP deployment with less risk and greater cost control.

With these solutions, service providers will no longer have to make investments in legacy equipment. Upgrades and expansions can be accomplished through cross-platform next-gen technologies.

During the past year, a few vendors have launched VoIP products that can be added to, or work in conjunction with, an existing TDM switch. These products have been welcomed by existing carriers. They extend the lifespan of legacy equipment without delaying the rollout of VoIP. In addition, they allow the service provider to have a planned and controlled VoIP deployment that is less likely to cause problems for customers.

Cirilium Inc., for example offers the i-Com cross-platform solution that includes enabling technologies that integrate across different platforms, performing functions such as call control, call management and provisioning. This means service providers using i-Com can deploy single applications that work across networks, including realtime billing.

The real value of such a solution is the ability to traverse multiple protocols. By integrating TDM protocols like ISDN, SS7 and CAS with IP protocols such as SIP, H.323 and MGCP, service providers can extend the investment made in circuitswitched technologies. They can migrate to VoIP solutions without replacing any part of their existing network.

After almost a decade, VoIP demand has finally started to take off. While it will take several years before the entire switching architecture in carrier networks is fully IP, service providers must finalize their nextgen strategies today. Then, they must successfully implement their road maps or they will find themselves playing catch-up to competitors and operating at a much higher cost.

Susan Cable has assumed various marketing management roles within Cirilium Inc. during the past five years. In addition, she owns and operates a marketing consultancy firm targeted to companies within the telecom industry.


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