By Kevin Kieller July 30, 2014 Leave a Comment
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SBC, SIP, ROI by Kevin Kieller

The world of unified communications (UC) is filled with acronyms. During a recent webinar I keynoted along with Alan Percy of AudioCodes, “SIP Trunking, Enterprise SBCs and the Return on Investment” it became clear to me that one of the most important acronyms to focus on is ROI, return on investment.

Return on investment (ROI) is tricky to calculate, measure and achieve:

ROI image 2

When we apply the concept of ROI to session border controllers (SBC) and session initiation protocol (SIP) we first need to understand the other two acronyms in play.

A Session Border Controller acts as the access interface between your IP voice infrastructure and the PSTN (public switched telephone network) via a SIP trunk (for both signaling and media).

ROI image 1

An SBC with a SIP trunk provides a connection to the PSTN as an alternative to using 1FLs or PRIs (two more acronyms: 1FL = one flat line or one family phone line; PRI = primary rate interface and can typically be “sliced” into 23 or 24 separate phone lines, sometimes also referred to as a T1 which as a data circuit that carries 1.544 MBps).

It is important to note that in a Lync environment it is only voice calls destined for “regular” phone numbers that traverse the SBC and SIP trunk. All instant messaging (IM), video calls and web conferences connect through the Lync Edge Server. Voice, IMs, video and content sharing sessions with federate organizations similarly connect through each organization’s Lync Edge Servers and do not involve the SBC or SIP trunk.

The main return on investment for SBCs and SIP typically focuses on the amount of money saved through migrating from PRIs to SIP trunk(s). The rationale is that with distributed PRI connections to the PSTN, you may end up purchasing excess capacity at multiple office locations. Because SIP trunks allow you to connect to the PSTN at a single point, you are able to aggregate capacity and are not required to over provision at each location. This aggregation means you may be able to purchase fewer total PSTN “lines” or “channels” when using SIP as compared to PRIs. 

An example may make this clearer. Assume an organization has three office locations. Each office location requires a total of 46 phone lines to meet their needs for inbound and outbound calls during the busiest time of the busiest period. Given this, each office currently has 2 PRIs connected to local equipment. (The organization pays for a total of 46 lines per office x 3 offices = 138 lines.)

However, consider that the busy period for different offices is during varied times of the year, given the different products they focus on, such that the maximum number of calls at any one time that the organization needs to handle is 110 (because two offices are not typically busy at the same time). This means that using a centralized SIP trunk connected to an SBC, the organization only needs to pay for 110 lines.

So using SIP the example organization can purchase 28 fewer lines. Additionally, some telecom providers are currently offering SIP lines (channels) at a lower cost as compared to PRI lines and most SIP services offer “burstability” which means you can pay for the average number of lines needed and still be able to accommodate seasonal peaks (bursts) above the contracted number of lines.

So using SIP can provide a “gain from the investment.” This simple example perhaps illustrates why Infonetics Research reported that adoption of SIP trunking services grew 220% worldwide in 2010 and is on track to grow at a CAGR (compound annual growth rate) of 35% through 2017.

But what is the “cost of the investment?” (Recall the original equation to calculate ROI.)

It turns out that SBCs are not free (this should not be a surprise). Moving from PRIs to SIP as your PSTN connection requires a change in the equipment.

Based on statistics compiled by AudioCodes and shared by Alan Percy during our webinar, it turns out that "A 'Like for Like' conversion from PRI to SIP Trunks in some cases results in a slim reduction in costs.” Alan pointed out that this was due to two primary factors:

  • PRI circuits are now more often priced competitively

  • Poorly managed SIP Trunking implementations can cost more than expected and any support issues can quickly negate possible savings

And this is where I argue that calculating the correct ROI becomes tricky.

In my experience, as I shared during the webinar, the gain from investment associated with implementing an SBC was not really about savings from moving from PRIs to SIP; but rather, the true ROI from implementing an SBC and SIP is more accurate when the “gain from investment” includes…

1.  Savings from adopting a centralized architecture.

With an SBC and SIP little or no equipment is required at branch offices. This often drives significant one-time savings. Further, the centralization and standardization of processes and support services that come with SBCs can provide additional ongoing cost savings.

2.  Getting the UC job done – and achieving your UC business case benefits.

With a UC implementation, an SBC acts as a firewall for the voice circuits. In this case, the additional security an SBC provides can help you address concerns from your security team that may “block” your entire UC deployment. This is especially true in a Lync environment where you can technically connect the Lync Mediation server directly to the SIP trunk, which may be fine for a pilot implementation, but often is disallowed when you try to scale the solution. In this case, an SBC allows you to achieve the business benefits estimated as part of your UC business case because it allows the project to proceed.

An SBC also helps you address protocol differences between your on-premises equipment and your SIP trunking provider. Because the SIP standard is evolving, even SIP trunks theoretically certified to work with a particular UC platform still need subtle “massaging” to work in reality. An SBC is well-suited to handle these subtle protocol and media transcoding differences.

Lastly, an SBC often helps you reach your end goal because it can transition calls from the “old” platform to the “new” platform. If all calls terminate on the SBC, it can route calls as appropriate, or even simultaneous ring both platforms, so that users can be more easily transitioned.

An SBC can certainly help you reach your maximal ROI but in addition, an SBC is an ideal point to measure and monitor voice usage and adoption. Because inbound and outbound calls flow through the SBC, it becomes an ideal point to track both usage and call quality. This tracking helps you ensure you are getting what you pay for from your SIP provider (concurrent channels) and that you are being billed correctly based on the services you are consuming (especially important if you incur “bursting” charges).

The world of UC certainly includes an abundance of acronyms and ROI is an acronym that is complicated to accurately determine. When it comes to calculating the ROI associated with SBCs and SIP you must think beyond a “like for like” transition from PRIs in order to determine the correct result.

Do you have additional thoughts on calculating or achieving ROI through UC with or without SBCs and SIP? Did your UC implementation meet its ROI goals? Please comment below, connect with me via LinkedIn, or send me real-time feedback via Twitter @kkieller.


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