Softswitches And The Future Of Voice
Networking
BY PEDRO COLACO
The convergence of voice and data is creating a host of new revenue
opportunities for service providers. Because data traffic is growing much
faster than telephone traffic, there has been considerable interest in
transporting voice over data networks. The ability to combine voice and
data on a single network represents a huge cost savings for service
providers who must currently support separate voice and data networks. As
a result, service providers are reevaluating the way they do business. In
order to succeed, they must respond to the changes in the
telecommunications landscape by providing differentiated services such as
Internet Offload, Tandem and access services, and VoIP.
IP Is The Major Driver For Innovation
VoIP, the ability to make telephone calls and to send facsimiles over
IP-based data networks with a suitable level of quality of service (QoS),
has become especially attractive to service providers who want to provide
voice and data services over a single network, since most networking
growth is IP-based. In fact, toll-quality voice over IP has now become one
of the key steps leading to the convergence of voice and data
communications. Adding voice to packet networks requires an understanding
of how to deal with system level challenges such as signaling,
interoperability, packet loss, delay, density, scalability, and
reliability.
But the value in deploying VoIP is that it is the right infrastructure
and the critical first step for service providers to enable revenue
generating enhanced IP services. VoIP involves much more than simply
adding compression functions to an existing IP network. By standardizing
on IP as the service layer, voice becomes just another application on top
of the infrastructure. This separation of application and transport will
unleash waves of service innovation unrealized up to now. One of the key
technologies enabling this separation is the softswitch.
The Value Of Softswitches
Softswitches are a class of equipment that uses software intelligence to
allow carriers to integrate voice services running on Internet Protocol
(IP) networks across existing Time-Division Multiplexed (TDM) and
Asynchronous Transfer Mode (ATM) telecommunications networks. Open service
creation and delivery platforms, softswitches allow providers to simply --
and cost-effectively -- integrate converged voice and multimedia services.
Their primary value is that they allow service providers to quickly and
inexpensively roll out new services without having to involve switch
vendors in the process. That is why softswitches create such promising
opportunities for service providers to quickly ramp up their Internet
revenues.
But picking the right softswitch is the tricky part. There simply is no
agreed to definition for a softswitch, but there is hope. Thanks to the
efforts of the International Softswitch Consortium, there seems to be a
developing consensus around the following definition of a softswitch:
- Interoperability and support for an open architecture;
- Scalability and bulletproof reliability; and
- Regulatory compliance and deployability.
Interoperability And Open Architectures
The important thing to look for when assessing the openness of a
softswitch is not necessarily to get bogged down in spec sheet details,
such as whether a product supports 1-800 features or a specific service
such as local number portability (LNP). It is as important to look at the
design to see whether it is open and extensible so that it will support
not only the current crop of revenue generating, value-added services, but
also new services that have not even been thought of yet. How can you
tell? Look for support for legacy and next-generation interfaces. A
softswitch needs to provide interoperability with other network components
through standard signaling protocols such as SS7 ISUP, TCAP, SIP, SIP T,
MGCP, and H.323. Utilizing these standard protocols, a softswitch can
provide multiple interworking solutions, including:
- Switching voice traffic between the PSTN and data networks (SS7,
MGCP, H.323);
- Interworking with other softswitches and application servers (SIP,
SIP T);
- Enable interoperability between legacy and next-generation VoIP
gateways and endpoints (MGCP, H.323, SIP); and
- Provide IP-based services seamlessly across voice and data networks
(SS7, SIP, MGCP).
These protocols will be the basis for easy and quick deployment of new
value-added services, which will include the "killer
applications" that will significantly enhance the revenue streams of
service providers.
Scalability And Bulletproof Reliability
It does not matter how much money the service provider can make from these
value-added bells and whistles if the softswitch itself does not scale to
supporting millions of subscribers, or is not reliable at the levels of
the PSTN. What is needed is a platform that delivers
"five-nines" levels of uptime; 99.9 percent will not do. One
approach to ensuring reliability is to run the softswitch software on
highly redundant, high-end servers. The snag is that these servers start
at around $400,000 and are not scalable. Worse, expensive hardware only
addresses half the problem.
To ensure maximum uptime, the software that runs on the server also
must be protected. A promising solution now gaining ground is to use
clustering software that can spread softswitch intelligence over multiple
servers. This approach increases the reliability of the network, since
clusters are less vulnerable to software bugs. Further, load balancing
features inherent in clustering applications also improve performance by
allowing processing tasks to be spread over multiple servers. Clustering
also cuts down on capital outlay because it allows less expensive server
hardware to be installed for between $30,000 and $40,000.
Regulatory Compliance And Deployability
Having an open, scalable, reliable softswitch does not indicate that the
product is deployable in a production networks. Signaling certification
(e.g., via Telcordia), number translation that meets the needs of service
providers, support for FCC regulatory issues (CALEA, LNP, and E911) and
operator/directory assistance are issues that are not evaporating with the
adoption of voice as an IP application. As such, it is critical to look
for the support of these functions, and also the field deployments that
have "shaken out" the early problems that any new product
encounters when it is introduced to live traffic.
Just A Part Of The Equation
When looking at a service, service providers typically think in terms of
end-to-end solutions. Therefore it is critical to take a look at two other
important components in terms of delivering the new multi-service IP
network: The mediation function between packet and circuit and the
underlying IP infrastructure.
First let's look at the mediation equipment (commonly referred to as
media gateways) that mediates between circuit and packet. These gateways
need to support cutting edge DSP technology to provide high density and
unsurpassed scalability, best-in-class voice processing (including
compression algorithms like G.726 and G.729/A), and especially quality of
service (QoS) integration with the underlying IP infrastructure for
edge-to-edge toll-quality voice. Integration of customer premise equipment
QoS is then critical to provide end-to-end toll-quality voice, which is
mandatory for voice service on any network. However, QoS is currently only
a discussion to have under "favorable conditions," which
typically do not exist in production networks.
As such, the underlying IP infrastructure needs to be upgraded to
support wirespeed interfaces, as well as wirespeed classification and
acting on that classification. These functions are mandatory in products
built to support the IP infrastructure that can carry voice traffic
reliably and consistently. But this new multiservice IP network needs also
to support "traditional data" services at the edge, such as
frame relay, ATM, and circuit-based point-to-point transport. Optical
equipment, while cost effective and feature rich, must maintain support
for the legacy network close to the network's edges in order to protect
the investment in the legacy network. Users will still be connecting to
the PSTN using modems where appropriate or cost effective, even as
broadband access is deployed and adopted.
Private line services, including leased data lines and voice tie-lines
will continue to be revenue generators for carriers, but they too will be
relegated to the application space. Private voice and data applications
can use IP VPNs as a replacement for private facilities. Interoffice IP
networks, today commonly frame relay-based, are also important services
and frame relay mediation is a necessary function of leading edge router
technology.
In Summary
There is no doubt the softswitch category requires a lot of thought and
consideration. But it is also increasingly clear that service providers
cannot afford to ignore this product class. Creating your own softswitch
definition and matching it to the available products is the fastest way
for a service provider to identify the product that will let them offer
new and varied voice service quickly and easily. But it is just as
critical to look at the edge-to-edge network solution including the IP
transport layer and the mediation layer. This new IP network must become
multiservice, allowing multimedia applications to generate revenue in
addition to transport access charges. Remote Access Service (RAS), Voice
Service, ASP, wireless multimedia, and other emerging services are the
future revenue generators for IP networks. Only by delivering
best-in-class offerings in all these segments will service providers
survive in this market. c
Pedro Colaco is director of product marketing for Unisphere
Networks' Voice Division. Unisphere assesses, develops, and markets
advanced technology by providing the technical, business, and financing
resources that transform prototype stage innovations into products that
compete successfully in the global marketplace. Please visit their Web
site at www.unispherenetworks.com.
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