Sizing SIP Trunks at Enterprise ConnectSizing SIP Trunks at Enterprise Connect

Your architecture, traffic levels, traffic load, and other factors will determine how much capacity you need.

The proliferation of Session Initiation Protocol (SIP) trunking has become an issue for IT organizations when performing bandwidth calculations and determining the number of SIP sessions for their SIP trunks. SIP trunking is financially attractive. SIP trunk providers also offer other features like least cost routing and bundled national and international services.

SIP trunking cannot be ignored. But it is important to size your SIP trunking to support the calling services that your enterprise requires and that your customers and other users have become accustomed to with legacy systems.

As your enterprise plans its migration to SIP Trunks, you'll need to understand the effects that voice (and potentially video) will have on traffic. You also need to understand how carriers charge for the capacity that you need to buy from them. That means figuring out how peak-hour traffic demands translate into IP metrics, as well as determining how to allocate capacity across multiple sites in a way that optimizes your spend without compromising your ability to deliver the needed traffic.

I will be presenting a short discussion of how to size SIP trunks as part of a session, "Right-Sizing Your SIP Trunk Procurement" at Enterprise Connect on Monday, March 17 at 3:15 PM to 4:00 PM.

In this session, you'll get both statistical and real-world information to help you make the calculations for right-sizing your SIP trunks. You'll learn about IP traffic engineering implications, as well as concepts that carriers are introducing, like "pooling," to let you dynamically allocate resources among sites for the best use of your resources.

We'll also discuss improper SIP trunk sizing that may occur. Issues in this area include:

* Over-design wastes money
* Over-design requires more bandwidth
* Too many SIP licenses are procured
* Under-design blocks calls
* Under-design frustrates customers
* Under-designed bandwidth will impact call quality
* All of these improper configuration issues, especially under-design, can diminish the enterprise's reputation

There is a two-step process for determining the required trunk capacity for incoming calls. The first step is ascertaining Grade of Service (GoS)--the probability that someone making a voice or interactive voice response (IVR) call will get a busy signal. This step uses an Erlang B formula and calculation. The second step is to calculate the bandwidth required to support the number of SIP trunks/lines needed to carry incoming calls, as determined by the Erlang B calculations.

Following my presentation, a panel will discuss the following questions:

* How do you translate your current traffic requirements for PRI metrics to IP/SIP Trunks?
* How do you purchase SIP Trunks while factoring in busy hour loads and sufficient quality of service?
* How do questions of SIP Trunk sizing vary depending on your network architecture--i.e., how do you size SIP Trunks at a centralized datacenter serving all your locations versus an architecture with local SIP trunks at multiple locations?
* How do you account for video traffic--current and future--in your SIP Trunk sizing?
* How do you translate the carriers' offerings and terminology into metrics and commitments that you can understand and rely on?

The panel members are:

* Mark Holloway, Master Principal Sales Consultant, Communications GBU, Oracle Corporation
* Mykola Konrad, Vice President and General Manager, Trunking and Policy, Sonus Networks
* Steve Lingo, Sr. Manager, VoIP Marketing, XO Communications

I look forward to your attendance. As SIP Trunking continues to be a popular topic at Enterprise Connect, we have had a large audience each year for the panel discussion and presentation, with highly engaged audience members.

Learn more about SIP Trunking at Enterprise Connect Orlando 2014!