The VoIP Peering Puzzle�Part 52: SBC Architectures�Solegy

Solegy Systems, LLC, is a privately held application service provider with the primary mission of developing a managed service delivery platform for VoIP and next-generation service providers. The company’s products provide the plumbing to support the next-generation applications that will proliferate on 4G and other future wireless networks. Headquartered in New York City, the company has over 90 employees in New York, Toronto, and Manilla, Philippines.

Solegy’s platform is designed to help service providers to launch new services in the shortest possible time. Appropriately named ServicePDQ, this service delivery suite combines application/feature servers, session border controllers, real-time rating and charging and other operations support system/business support system (OSS/BSS) functionality into a single coherent system.

Because all solutions have been developed in-house, drawing on over seven years of research and development for other leading VoIP solution providers, Solegy claims that ServicePDQ is inherently more flexible than multi-vendor solutions, and that their platform takes the complexity out of the normally mundane but critically important aspects of providing a real-time service. Pre-built applications for VoIP service providers include prepaid calling cards, postpaid calling cards, broadband telephony, hosted PBX, voice messaging, and wholesale peering.

As a byproduct of this application development, Solegy’s Chief Technical Officer, Joegen Baclor, founded the OpenSIPStack Project (see in January 2005, to provide software developers with a platform-agnostic stack implementation of the Internet Engineering Task Force’s Session Initiation Protocol (SIP) standard, documented in RFC 3261 (see The OpenSIPStack code can be compiled in Linux, Solaris, BSD, Darwin, and Windows systems. This library presently contains core implementations supporting the User-Agent, Back-to-Back User Agent (B2BUA), Third Party Call Control (3PCC), Proxy, and Registrar functions.

In addition to the OpenSIPStack, three applications are available: ATLSIP, an ActiveX Control SIP User-Agent with audio functionality, OSSPhone, a full-featured SIP User-Agent with audio functionality, and OpenSBC, a full-featured session border controller implementation.

OpenSBC was released in March 2006 under an OSI-approved open source license, and offered though a sponsored community called OpenSourceSIP, which is also sponsored by Solegy (see OpenSourceSIP is a vehicle that Solegy created to promote certain software that it decided to make available as open source. All of the primary contributors of source code for OpenSourceSIP projects are Solegy employees.

The OpenSBC element of this project is something that Solegy claims is the first open source product designed to specifically to perform session border capabilities. These include admission control, far-end NAT Traversal, topology hiding, media anchoring, SIP privacy enforcement, session limiting, and CALEA filtering. OpenSBC has been benchmarked to handle 60 calls per second on a 1.6Ghz AMD Opetron CPU with 1GB of RAM. The same server can easily handle 1,200 concurrent calls, although capacity will vary depending on the usage scenario.

While the OpenSBC will run on any version of UNIX, the company prefers to use Open Solaris. The core SIP stack that forms the basis for all the open source SIP projects, including OpenSBC, was authored by Baclor. All of the derivative open source SIP software, including OpenSBC, is original work product created by Solegy and is currently maintained and updated by the company’s software developers.

Solegy released the OpenSBC to the open source community as part of its strategy to encourage the creation of next generation SIP-based applications. As the primary border element on the session control plane, the OpenSBC provides a framework to easily abstract the business policy and logic from other components of the next-generation ecosystem. When used in conjunction with the ServicePDQ suite, third-party service providers can easily utilize core ServicePDQ functions such as real-time rating, advanced routing, and presence management, to name just a few.

Solegy’s core competency is in providing the OSS/BSS elements that add value to session border controllers, rather than looking to compete with other SBC providers or other companies that produce media processing solutions. Accordingly, OpenSBC is an enabling technology that allows them to more easily demonstrate the power of Solegy’s higher-level platform. In the future, Solegy expects that the evolving IMS and 3GPP standards will allow its platform to interoperate with other SBCs and session plane applications.

In the meantime, however, OpenSBC is free to use, and, being open source, allows technically capable network managers to look under the hood and make modifications. If you’re one of those that can’t wait to take that peek, check out the impressive software manual at And who knows, perhaps Solegy’s OpenSBC idea will really catch on, taking on a life of its own, much like Digium’s Asterisk has within the software-based PBX industry.

Further details on the Solegy architecture and products can be found at Our next tutorial will continue our examination of vendors’ SBC architectures.

Copyright Acknowledgement: © 2007 DigiNet Corporation ®, All Rights Reserved

Author’s Biography
Mark A. Miller, P.E., is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.

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