SIP Trunking and Demarcation

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SIP Trunking and Demarcation

By TMCnet Special Guest
Alan Percy, AudioCodes
  |  October 02, 2013

SIP trunking is widely recognized as an alternative to legacy PRI circuits, delivering voice services to businesses over IP at reduced costs with greater flexibility. Partners are also seeing opportunities to resell SIP trunking to their business customers, creating a revenue stream and earning residual commissions.

However, delivering and maintaining voice quality that matches the expectations of businesses migrating from PRI circuits is critical to success. Having a clear point of demarcation between the SIP trunk and the business voice network where voice quality can be measured is becoming increasingly important for partners, businesses and service providers. As with legacy TDM trunking, a point of demarcation allows partners to identify whether the issue is the responsibility of the service provider or an issue in the customer’s network. Without it, voice quality issues turn into a circus of costly finger pointing with little access to hard data to prove responsibility and help isolate the issue.  

Demarcation for SIP trunks is a natural role for enterprise session border controllers – specifically designed for positioning at the enterprise premises (or their private cloud data center), already providing a number of important functions:

Interoperability – allowing different implementations of SIP to interoperate via message header manipulation, dial plan fixes and even conversion of the media streams from one codec to another (transcoding). The interoperability role has shown to be especially important when integrating Microsoft (News - Alert) Lync to SIP trunking providers or other SIP-based applications.

Security – by protecting the enterprise network from attack and theft of services, session border controllers are essentially firewalls on steroids, using an understanding of the SIP protocol to dynamically open and close UDP (News - Alert) ports for media, detect and protect against registration floods, authenticate access and a variety of other means to guard against abhorrent behavior that would otherwise disrupt business activities.

Survivability – detecting network or service provider interruptions and redirecting traffic to alternate providers, either back-up last-mile facilities, SIP trunking services or legacy PSTN circuits.

Only recently has the role of voice quality monitor and demarcation with SIP trunks been fully recognized as a primary driver for use of E-SBCs.  E-SBCs facilitate voice quality monitoring on media streams as they traverse the E-SBC, measuring jitter, dropped packets and other network statistics, and then periodically reporting statistical information to a centralized network management systems.  

We at AudioCodes (News - Alert) facilitate voice quality monitoring and demarcation by offering a combination of our Mediant E-SBCs with embedded quality of experience software, along with our Session Experience Management centralized network management tool. The combination provides a visual dashboard that shows network performance status and history at a glance. With AudioCodes E-SBCs and SEM, partners can improve customer visibility to voice quality, more quickly isolate and resolve issues, and reduce costly finger pointing.

AudioCodes Mediant Enterprise Session Border Controllers and Session Experience Management software along with other related network elements are all part of AudioCodes’ One Voice for Lync offering, a comprehensive portfolio of voice network elements, a team of highly-experienced professional services, and a global support network together from one source. By teaming with AudioCodes and leveraging One Voice for Lync, partners can be more efficient, win more deals and in the end, be more successful.

AudioCodes, a Microsoft Communications Gold Competency partner, designs, develops and sells AudioCodes One Voice for Lync, a comprehensive portfolio of voice networking technology, professional services and global support, optimized for Microsoft Lync and Exchange Unified Communications (News - Alert) solutions. Sold through a global network of highly-trained reseller partner community, AudioCodes One Voice for Lync simplifies the selection, implementation and support of Unified Communications. Whether deployed on premises or in the cloud, AudioCodes is the One Source for Microsoft-certified products and services.

Alan Percy (News - Alert) is senior director of marketing at AudioCodes ( He can be reached at

Edited by Alisen Downey
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