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June 2001

Dick Hayter Softswitch: One Size Does Not Fit All


In the coming years, service providers face the task of integrating new voice-over-packet technology with their existing infrastructure. With data traffic outpacing voice, carriers will need to transmit data cost-effectively and cap spending on legacy equipment while investing in new technologies. There are many factors that must be considered in their network and services planning -- including such critical aspects as capital budgets, scalability, interoperability, reliability, service creation flexibility, application requirements, and physical installation constraints.

Clearly, the appeal of the softswitch in next-generation networks (NGN) is that it is an unbundled alternative to the expensive, proprietary circuit switch in the PSTN. Through softswitching, a distributed architecture and centralization of intelligence provide economy through the inherent ability to adapt, change, and scale. This unbundling translates to lower start-up and operational costs, reduced dependence on switch manufacturers for service development, and dramatically compressed lead times for new service introduction.

The service providers, however, will have vastly different requirements for the softswitch solution depending on their particular market or implementation scenario. For example, an enterprise adding a voice overlay to an existing ATM network needs a very different implementation than an IXC considering Class 4 tandem switch replacement, an ILEC planning to add out-of-region service, or a CLEC requiring an Internet offload solution

The Right Solution For The Right Price
Rather than relying on a "one-size-fits-all" box, the successful end-to-end network vendor needs to create a family of softswitches, with a price point and capacity structured to match the needs of specific customer implementations. Each softswitch delivers the required capacity to drive particular applications or services. The products, based on a scalable, common hardware platform, can be easily upgraded to the next higher-capacity product. The matched set of application and hardware platforms is key to providing the "right solution at the right price" for all customers.

Unbundling Services
In general, switch requirements will be greatly affected by application content and location in the network. Service at the edge of the network will require more applications and, therefore, will be more complex. Adding CLASS services to a tandem replacement media gateway controller (MGC) will have the negative effect of reducing capacity, increasing complexity, and causing more switch interdependency. However, feature control can be separated from the MGC with the addition of an application feature server to help reduce the complexity of service creation and implementation and allow further customization. This additional unbundling drastically lowers the cost barrier to enter new markets and achieves unprecedented economies of scale. Greenfield carriers, for example, can outfit new markets with media gateways and feature servers controlled by a centralized MGC, instead of full-blown Class 5 switches. Incumbents can maintain the same service quality by using larger gateways in established markets and smaller gateways in new out-of-region markets under control of a location-independent MGC cluster.

The Impact of Softswitch Applications
A distributed packet tandem application must allow the carrier to cap their investment in circuit switches by delivering the features of a traditional Class 4 switch -- flexible routing and number translation, N00/888 translations, routing restrictions, authorization, and screening. Due to a substantial installed base and large call volumes, the critical performance characteristic is call capacity, likely in the range of 800,000 busy hour call attempts (BHCA) including consideration for ever-present AIN dips.

However, for Internet offload, the requirement is essentially to redirect Internet-bound traffic from the overtaxed Class 5 central office switch to the packet network. Call capacity requirements for this particular application may only need to be 250,000 BHCA, largely due to the longer hold times associated with data calls. Customers in this category are inclined to pay for scalability but not unneeded capacity.

Fulfilling The Promise
Network implementation requirements will obviously vary, and the softswitch product offering will be segmented in order to optimize the value proposition to the customer. The service provider will effectively choose a network element according to call performance, feature support, and pricing. In-service capacity upgrades and added feature provisioning will be added as required, quickly and easily.

A segmented softswitch product line facilitates the migration to packetized voice networks for both early adopters and incumbents alike. It fulfills the promise of operational cost savings, increased flexibility, and differentiated service offerings for all customer implementation scenarios. In the adaptable, open architecture of next-generation networks, one size softswitch does not fit all.

Richard (Dick) Hayter is the assistant vice president of marketing for the Network Systems Division of Tekelec. Tekelec, a leading supplier of signaling and controls systems, develops innovative network switching and diagnostic solutions enabling the convergence of traditional and converged wireline, wireless, and IP voice and data communications networks. The company also provides products and solutions for call centers and other telecommunications markets. 

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