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What Every Business Needs to Know About Implementing SIP Trunking

Posted by Kevin Gulley

Feb 3, 2016

In previous posts we’ve discussed the basics of SIP Trunking and the business benefits it offers. Now I’d like to examine SIP Trunking from an implementation standpoint, and take a look at what businesses can expect when they decide to take the leap toward SIP. In a podcast interview I recently had with Steven Johnson, North American president of InGate Systems, a Swedish company that develops Firewalls and Session Border Controllers and helps businesses effectively implement and secure SIP trunks. In our conversation, Steven and I discussed some of the nuts and bolts of how to implement SIP Trunking in a practical way.

What is SIP and What Does it Replace?

Implementing SIP Trunking Best PracticesSession initiation protocol or SIP has been around since the late 1990s, but the adoption of it into the mainstream business environment has been a slow and gradual process (although it is seriously hockey sticking right now!). That slow growth may have been because of the perceived reliability and ubiquity of the traditional TDM phone system. But as Steven pointed out, that technology hasn’t really changed much since Alexander Graham Bell invented it more than 100 years ago.

The “session” in session initiation protocol can be thought of as a single conversation that takes place over a phone line. The protocol sets up and breaks down that session.  That being said, SIP can be used for any form of media, such as video conferencing, screen sharing, instant messaging, etc., and unlike a traditional telephony network, instead of just voice, SIP can handle all the different forms of communication.

What SIP does is  replace TDM by using the Internet, or what we traditionally think of as data lines. In doing so, the result is one set of wires that serves all needs – data voice and video. There is no longer any requirement for a dedicated voice network. What’s more, according to Steven, “One thing that most people don’t realize is that right now the phone companies are using IP for most of their long-distance calls. So when you make a call, your call is converted to SIP and sent over the Internet rather than using the dedicated copper or fiber lines of the past.”

He went on to explain that both AT&T and Verizon have publicly stated their intention to do away with their legacy TDM networks by the year 2020, meaning all traffic will be handled by SIP trunking.

Key Considerations When Implementing SIP Trunking

Bringing in all traffic over a single network may make some operations folks a little nervous to say the least. The fact is, however, that using the Internet as a communications medium allows for the removal of many points of potential failure. There’s no more need for multiple PBXs, dedicated telephony, and localized trunking.  

The result is less equipment, less maintenance, lower costs and a single set of hardware that can be managed centrally and rolled out to remote locations. Related: How SIP Trunking Provides Real Savings for VoIP and other Unified Communications (UC) Traffic  And that’s not to mention the ability to carry video – an option that wasn’t even available on the old telephone networks.

Another consideration is the disaster planning/disaster recovery scenario. Imagine a central facility that houses a company’s primary phone system. What happens when that facility is rendered inoperative? A complete loss of telephone communications usually results. With SIP, as long as you have an Internet connection, regardless of where you are physically, you can communicate.

4 Things Companies Need to Do to Prepare for SIP

  1. The first thing any company that’s considering a transition to SIP Trunking should do is perform an assessment of their existing infrastructure. Do they have enough bandwidth and is their network (routers, switches, wired/wireless connectivity) robust enough to handle the increase in traffic?
  2. As with any major upgrade of a system, there is an investment in both time and capital cost. However, unlike the proprietary systems of the past, there are far more options and alternatives with SIP. That said, yes companies will need to upgrade their PBX to handle SIP calls, which may mean new SIP-based cards, or a new PBX or migrating to a new UC or UCaaS platform. There are also cloud-based software or virtual implementations of PBX available.  
  3. Deskphones may need to be upgraded to SIP enabled IP phones.  Most UC systems also offer softphone options as well as mobile apps that handle all SIP-based calls as if they were coming into a deskphone.
  4. Another crucial item is a full-featured Session Border Controller (SBC). As we know, a SBC is analogous to a firewall, but is designed specifically for SIP traffic. The SBC also allows for interoperability between a company’s PBX and the service provider, when there are differences between implementations of SIP.

Wait, differences in implementations of SIP?

Let’s clarify. Everyone implements SIP using the standard set by the IETF, but within the definition of the standard SIP protocol, there may be two, three or more different ways to handle a particular function like a transfer. So, the SBC translates between these different ways of implementing SIP. Think about it in terms of regional dialect – same language, but different idioms or pronunciations.  An SBC “normalizes” the traffic between the carrier and PBX.

The SBC also performs a security function, making sure no one hijacks a session or launches a DOS attack. It also does routing, allowing for multiple PBXs and even different carriers, for redundancy and failover purposes.

The Bottom Line - The Time To Implement SIP is Now

For companies considering the transition to SIP Trunking, there’s really never been a better time to do so. The reliability, relatively low cost of implementation, and options for equipment and carriers mean that companies have more choices than they’ve ever had.

These days there are even Internet Telephony Service Providers who do nothing but SIP. Think of these guys as the so-called disruptors. In the past they couldn’t compete with the big telecoms because of the enormous barriers to entry of the communication networks. But with SIP, they don’t need the massive infrastructure – or at least they don’t need to own it themselves. All of a sudden, they can play on a somewhat level playing field. And because they don’t have the legacy costs of Ma Bell, they can offer some pretty good deals.

As for what the future holds for SIP, the standards and features are pretty much established. Any company choosing SIP now will likely have many years of reliable and stable service.




Topics: Voice, video, Best Practices, SIP, VoIP,, Phones, Implementation, Telephony