ITEXPO begins in:   New Coverage :  Asterisk  |  Fax Software  |  SIP Phones  |  Small Cells

Packet IN
January 2001

Richard Hayter  

Will The Softswitch Fulfill The Promise Of AIN?


The telecommunications landscape is being transformed by the convergence of voice and data networks with next-generation switching technology. At the heart of the evolving packet network is the media gateway controller (MGC) or softswitch, which provides intelligence and call control to the network by directing sessions between endpoints across ATM, IP, and circuit networks. The softswitch enables the transition from circuit-switched to packet-switched networks, interfacing to the PSTN through Signaling System 7 (SS7).

The softswitch offers many advantages to service providers, beginning with the fact that the combined MGC and media gateway (MG) are typically at least 50 percent less expensive than the comparable circuit switch they replace. Softswitches and MGs are built on general computing hardware, and so, realize price/performance improvements that double roughly every 18 months, in keeping with Moore's Law. The softswitch frees providers to create networks built on best-in-breed products, rather than being tied to a single vendor's end-to-end, proprietary solution.

While cost savings can be a compelling argument for the new architecture, the greatest advantage of the softswitch is its role in service delivery and creation. The MGC, an open service platform, allows providers to leverage existing Class 4/5 services via the SS7 network and -- with the benefit of application program interfaces (APIs) -- create innovative, customer-driven services that are not possible in proprietary environment.

The concept of creating an open network where new services can be deployed faster and less expensively is not new. It has its roots in the advanced intelligent network (AIN) movement of the 1980s. Before the advent of the AIN, service providers were forced to rely on their switch vendors for service creation. That dependency resulted in long and expensive service development cycles. If a carrier had switches from multiple vendors deployed in the network, provisioning was a nightmare.

Prior to AIN, there was no way to interject intelligence into the network or alter the call flow. The AIN model decouples the service logic from the transport logic, allowing the network to change call routing moment by moment. There is virtually no limit to the number of actions the network can take on a call.

However, the AIN's vision of creating a device-independent network in which services are separated from the network switch has never been fully realized. Implementation presented a number of problems -- many of the advanced AIN features simply could not be deployed on legacy customer premise equipment. This was compounded by the fact that vendors created different AIN implementations, many of which proved to be incompatible.

Although AIN did not achieve ubiquitous deployment, the architectural model did lay the foundation for next-generation, IP- and ATM-based networks. These networks may fulfill the AIN's promise of putting service creation in the hands of the carriers and providers.

Fundamental to this new model is an open, nonproprietary architecture that unbundles the functions of the legacy central office. As in the AIN model, call control logic is separated from switching and service logic. This decoupling allows all types of media traffic to be carried on a common, core data network under the control of the softswitch. Flattening the network simplifies administration and maintenance and reduces network infrastructure costs. Carriers are able to implement "best-in-class" network elements and are freed from the expense and long development cycles previously associated with enhanced service delivery in the PSTN.

There is still debate as to where the services will actually reside -- on service control points (SCPs) in the SS7 network, onboard the MGC, or on SIP-enabled application servers with open application programming interfaces (APIs). It is likely that a hybrid, or combination of these approaches, will evolve. Rather than recreate existing services such as toll free and local number portability, providers will most likely deploy them from SCPs. Resource-intensive tasks and session state control will reside on the softswitch platform to maximize performance, while third-party feature development for new services will be handled through application or feature servers.

The softswitch's success and ultimately that of the new network model will hinge on a number of factors. The creation of an open architecture built on standardized protocols such as MGCP, SIP, and MEGACO is essential to enabling multivendor product interoperability. The softswitch itself will be required to communicate with multiple switching platforms via multiple standards to enable interdomain exchanges. Since the softswitch handles many of the functions of the central office switch, MGCs must scale to support large carrier networks and match the PSTN's benchmark of "five nines" reliability.

If the softswitch is to usher in a new network model, it will have to do more than simply replicate Class 4 and 5 features in a packet format. It must also to add value to the network by delivering a rich set of new and innovative features. These new feature sets will ensure the revenue stream for next-generation service providers.

Richard (Dick) Hayter is the assistant vice-president, marketing for the Network Systems Division of Tekelec. Tekelec, a leading supplier of signaling and control 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. 

[ Return To The January 2001 Table Of Contents ]

Today @ TMC
Upcoming Events
ITEXPO West 2012
October 2- 5, 2012
The Austin Convention Center
Austin, Texas
The World's Premier Managed Services and Cloud Computing Event
Click for Dates and Locations
Mobility Tech Conference & Expo
October 3- 5, 2012
The Austin Convention Center
Austin, Texas
Cloud Communications Summit
October 3- 5, 2012
The Austin Convention Center
Austin, Texas