Building Reliability using Session Initiated Protocol (SIP)

Building Reliability using Session Initiated Protocol (SIP)

SIP isn’t a four letter word, but for many years it might as well have been for most of us trying to use it. The results of a SIP deployment could be messy: poor voice calls, issues with phone features, and dropped connections only scratch the tip of the iceberg. Despite this our clients have often insisted they wanted to deploy SIP to save money. Along the way we have learned some valuable lessons. There is a right and a wrong way to deploy SIP, and I am sorry to say there are good and bad reasons to deploy it, too.

The right reasons to deploy SIP

  • Your network is setup to support it
  • It adds an additional layer of redundancy to your voice solution
  • You need to offer out-of-market telephone numbers
  • You need to run multiple businesses through a single phone
  • You want your PSTN (public switching telephone network) connection to sound like your after work drinking habits

The wrong reasons to deploy SIP

  • To save money
  • Because someone told you it was great
  • To showoff to your IT friends about how cutting edge you are
  • As a way to get a pesky sales guy off your back

Wanting to save money with SIP isn’t an inherently bad goal, but if it is the primary goal there are better ways to approach cost savings. Today we will focus on how to build a reliable SIP solution and even use the tools to increase your redundancy and ensure you look like an IT god.  

Preparing to SIP

Deploying SIP is attacked best in one of two ways. The most proven methodology is to get your SIP trunking from the same provider you receive internet access from. The carrier can then provide QoS across their own network, a primary concern with SIP, and can convert it to a format that works for your existing system. Some systems play well with SIP natively, others require a session border controller to mold it to their specific tech and still others will require you convert it to legacy type connectivity, think POTS lines or PRI.  Your single carrier will often provide this. Carrier delivered SIP is still the most comfortable for those unfamiliar with SIP technologies.

An alternative to SIP provided by the same carrier is an offering from a 3rd party. These offerings tend to add additional value, be less expensive, and are carrier agnostic. The disadvantage of this strategy is it requires more skill and knowledge to deploy correctly.  It is critical you understand the nature of the bandwidth coming into your building and have a way to shape and manage it.  A combination of hardware is needed to truly provide predictable and steady service. The first piece is your SD-WAN solution; the solution needs to be able to identify and then prioritize the SIP traffic coming to and from your locations. The second piece to add is a session border controller to convert the SIP to something your PBX will recognize, or as an alternative you can deploy an Adtran Integrated Access Device and deliver PRI or POTS converted into your existing system.


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Failure…or Success

Traditional dial-tone is difficult from a redundancy perspective. Asking technology as old as our telephone network to perform magic tricks by failing between various physical connections is near impossible. With SIP we get to shift this paradigm. Using 3rd party SIP trunks (most dedicated providers cannot fail off their network) allows you to point the service at an IP address but also offer a secondary IP address for routing. This could allow you to have a second site or second circuit backup a primary, as we typically do in a data world. In the event the first IP address is unreachable, the traffic will re-route to its second path. With this simple move you have created no single point of failure for connectivity to the phone network.

Let’s get Cellular

Not all of us have a second path, or want it used for voice traffic. In this event many providers will allow you to fail calls over to another number or numbers. These numbers could be your backup call center, an alternate location, or even cell phones. This is a very popular solution for many businesses, especially those with a single site. The cost of a redundant circuit may not be justified with voice alone, instead they opt for the cellular failover and gain the value of SIP.

Auto-Attendant Saves the Day

At the core, most of these SIP providers are also our hosted voice providers. Typically, the SIP offerings, especially from 3rd party solutions, include the availability of a cloud auto-attendant. This is a really nice add-on that gives your organization a face during an outage. If your phone system loses connection to its SIP service, it can be backed up by a voice in the cloud. Simply record your greeting and menu items when you sign up for the service and when/if that puppy goes down, your voice is still there, reassuring your clients that you’re only temporarily unavailable.

The Takeaway

SIP is here to stay; the carriers already use it as the backbone of the network, converting it when it reaches your office. The advantages can be pretty tremendous, but if the deployment is not well thought out it can be egg on the face of those responsible. Although we are less dependent on phones than we once were, our reputation is still damaged if our phone system goes down, and clients can’t reach us. By using SIP we greatly reduce risk and can, at the same time, gain other advantages listed above. Do your research and work with an expert in deployments to ensure success, and you can take advantage of SIP as well!

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Author: Kyle Holmes