The Softswitch in the Call Center

By John Jones

The definition of a softswitch is nebulous at best. Some manufacturers will use a very narrow definition that fits the functions of their product. At the other end of the spectrum, a definition that includes everything proposed for a softswitch may be unrealistic. It seems as if each author or manufacturer will include a different set of features or functions in their definition. There has even been discussion as to whether ‘soft switching’ even exists. I will try to cut through the clutter surrounding the concept, and show how the softswitch fits into the call center environment.

One concise definition of a softswitch is “a software application that performs the functions of a traditional telephone switch”. Paramount among these functions is call control. Although this definition ignores the runtime platform, some sort of standard hardware is assumed. Other definitions of a softswitch include the hardware necessary to connect to the varied services available both from standard and enhanced service providers. A softswitch can provide a unifying, flexible control point for varied telephony services, even to the point of creating new and unique features based on those services. Within the set of functions normally associated with a softswitch you will find a range of function from simple routing to functionality beyond that of a Class 5 central office switch. The Softswitch Consortium, an international group of manufacturers, developers and vendors defines a minimum set of functions for a softswitch:

  • Intelligence that controls connection services
  • The ability to select processes that can be applied to a call
  • Routing for a call based on signaling and customer database information
  • The ability to transfer control of the call to another network element
  • Interfaces to and support for management functions

All of these functions have been incorporated into Telescan’s Prism product. The need for softswitches is brought about by the evolving nature of telephony services and their delivery. Traditional services have been delivered over a circuit switched network. This is the familiar PSTN, or Public Switched Telephone Network in which there is one trunk or ‘port’ per call whether that port is delivered on an analog or a digital circuit. Once a call has been set up, bandwidth is guaranteed for the life of the call. This can be very resource expensive since resources are allocated and unavailable for other uses even during idle periods. Today, there is an accelerating migration to packet switched network architectures. In this type of architecture, data is formatted in blocks called packets, each with information about its source and destination. When sent, the packet is automatically routed through the network to it’s destination. With this mechanism, bandwidth is only needed when the data is in transit since there is no direct, one-to-one relationship between a call and a port.

The inherent differences between these two types of network necessitates some sort of converter or mediator to bridge the two networks. This is another function of a softswitch. You may have seen the term ‘convergence’ in the context of telephone and network services. This refers to the increasing blurring of the distinction between voice and data. Once you grasp the concept that ‘voice is just one kind of data’, this convergence begins to make a lot more sense. Voice over IP is one example of using a data network to provide voice services. The one aspect of voice data which forces special handling is its time critical nature. It does make a difference if voice data packets arrive out of sequence, it does make a difference if current traffic forces a delay in packet transmission. These are issues that must be addressed in any implementation of a merged voice and data network where both share transmission bandwidth as in an IP network. It is interesting to note that the providers of packet switched transmission services are often not the traditional telephone service providers. Also, these services are often ‘flat-rate’ rather than usage billed. This opens the possibility of reselling available bandwidth for enhanced services.

How does all this impact the traditional call center? The most obvious way is in the types of services expected by your clients. The requirement is there for a wide variety of messaging formats and telephony services, all accessible on demand. This demand is the driving force behind the implementation of unified messaging services. Another benefit of the softswitch concept is that it ties together solutions and services from multiple vendors. The call center is not ‘locked in’ to a single source.

As the nationwide and global networks evolve, it will be more likely that new services will only be available via packet switched networks. The call center must have access to these networks to use these services and remain competitive. This is where the softswitch will likely find its place in the call center of the future.

Telescan, LLC has been in the business of providing state of the art solutions to call centers since 1976. It’s newest major product, the Prism Digital Switching Platform, with its ability to bridge both circuit and packet switched networks, provides the flexibility and capacity to carry call centers into the future.

Bob McCammon, of MobilPage, Inc. in St. Joseph, Missouri has recently installed a Prism switch. He writes, “With the Prism, we can interface to our 26 DID trunks from four different central offices and 11 direct inbound customer lines into our call center. Many of the 8000 plus DID numbers we have are used for radio paging. The Prism will route on a per number basis to the live operator, voice mail, paging or our office phone system. All of the custom Auto Answer, hold overflow and system greetings are stored within the Prism switch.” With the Prism’s softswitch capabilities, he can also be confident of being able to keep his call center on the leading edge of client services in the coming years. John Jones has been chief engineer and director of engineering at Telescan since 1988. He has had a major role in the development of Telescan’s Earth-Net and Prism call processing systems.

[From Connection Magazine – March 2001]

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