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This article, by Martin Taylor, VP of Technology Strategy, MetaSwitch, originally appeared in Paradyne Broadband Times Newsletter, 21 April 2005.
The telecom industry is facing the biggest upheaval in its entire history, and Voice over Internet Protocol (VoIP) is the root cause. There is now no question that VoIP will have a profound and far-reaching impact on all voice service providers in the next few years.
But what does VoIP mean to rural independent operating companies?
What's wrong with the traditional time-division multiplexed (TDM) techniques
for voice switching and services? Why should IOCs think about adopting VoIP
in their networks, and what's the best way to go about it? In this article,
we address these important questions to help IOCs to pick their way through
the complex issues surrounding VoIP.
At first glance, it is not at all obvious why VoIP will replace TDM as the foundation of the voice networks of the future. After all, TDM technology has evolved over many years to provide an efficient and robust basis for voice communications, while the origins of IP lie in the very different world of data communications between computer systems. Making voice communications over IP work well has required a huge amount of innovation in both silicon and software to address such problems as bandwidth efficiency, voice quality, and network security.
So why is all this effort worthwhile? TDM technology as the basis of voice networks does not seem to be broken, so why does it need fixing?
The answer lies mainly in the economies of scale that are driven by data networking. Total Internet traffic surpassed total global voice traffic for the first time in 2002, and Internet traffic continues to double roughly every 6 months, while voice traffic is growing much more slowly. In the next few years, voice will represent only a few percent of global network traffic. Network equipment vendors have invested massively in silicon for switching and processing IP traffic, resulting in dramatic cost reductions. Despite all the extra technical complexity, it now costs considerably less to switch voice in IP packets than it does on TDM circuits, and the gap is growing fast. As a result, the traditional vendors of voice switching equipment have abandoned TDM, and are now focusing entirely on VoIP. All next-generation voice switching products will be VoIP-based.
When the existing TDM switches in IOC networks reach end of life, they will have to be replaced with VoIP switches because there won't be any new TDM switch products available. Some IOCs will choose to defer the introduction of VoIP in their networks until this time comes. For others, there will be compelling reasons to start working with VoIP switches far sooner. We'll look at these reasons next.
The need to deliver broadband services, including Internet access and digital TV, is driving the modernization of the access network. Early deployments of DSL involved an overlay approach, where DSL Access Multiplexers (DSLAMs) were installed alongside the POTS access network, but increasingly Broadband Loop Carriers (BLCs) are the favored solution. A BLC is an access device that supports POTS and DSL on a single integrated line card. Subscribers connected to BLCs receive conventional POTS service, as well as (optionally) DSL service. However, the BLC converts POTS traffic to VoIP and sends this traffic back to the Central Office on the same IP network as the data and video traffic. This integration of multiple services over a single IP-based access infrastructure enables BLCs to deliver substantial capital and operational cost savings relative to traditional access networks.
Access networks based on BLCs can be connected to traditional TDM voice switches by installing a terminal in the Central Office that converts VoIP access traffic to a GR-303 interface. However, VoIP can delivered directly into next-generation VoIP-based switching systems. This saves the cost of the CO terminal equipment, and may also save GR-303 upgrade costs on the switch. These savings alone may justify the installation of a new Class 5 softswitch alongside an existing Class 5 switch as part of a "cap-and-grow" strategy.
VoIP creates a number of new opportunities for IOCs to offer voice services to subscribers outside their normal territories. For example, IOCs can use VoIP to target under-served small business customers in neighboring regions. While TDM-based networks could be used to connect out-of-region subscribers, VoIP offers a much greater range of access options. For example, a competitor's DSL access network could be used to provide VoIP connectivity to out-of-region subscribers. Where aggressive penetration of out-of-region markets is planned, access equipment such as BLCs can be installed in collocation facilities. Other techniques such as wireless broadband or cable networks may also be used to support VoIP access...