SIP Trunking - Bundled or BYO?

Alan Percy : The SIP Invite
Alan Percy
| Observations by Alan D. Percy on VoIP enabling technology, industry and our personal reach for success.

SIP Trunking - Bundled or BYO?

While on the road this spring I had a number of very active conversations with our partners and customers about the delivery mechanisms, services and bundling of SIP Trunking here in the US.  It seem there are some patterns that I thought would be useful to share.

First I'm going to assume that you know that SIP trunking is a replacement for legacy TDM trunking lines that connect various size enterprises to the public network.  SIP trunks offer similar services, but instead of using dedicated TDM T1/E1 or analog telephone lines, the voice traffic is transported over IP-based data circuits.  SIP is used as the signaling protocol, controlling the start and stop of each voice conversation, associated caller ID and other enhanced services.

SIP trunks are not all created equal though - there are some very significant differences in the way they are sold and the services they support. I could spend months going into all the various technical and business model differences between the vendors, but today I'm just going to concentrate on the different ways they are delivered to the customer.

Tightly Bundled SIP Trunks
These typically are tightly tied to data services that would come from the service provider.  In this case, the service provider requires that you use their data infrastructure to carry the SIP trunks. They arrange for the last mile circuit, provide all the equipment and provide the services with one bill. The logic the service provider uses for this offering is that unless they can control the data infrastructure end-to-end, they can't guarantee the voice quality.  The biggest benefit of the bundled services is that it gives the customer "one throat to choke" if there are issues with the service or quality of calls.  

However, I've heard some push-back from customers on this "take it or leave it" business model, requiring that they buy both the broadband and voice services together.  In some cases the cost reduction doesn't justify the complexity and risk.  What if the enterprise already has an established relationship with a broadband provider and is under contract?  Do they need to pay to break the contract?  What about the risk of potential disruption while migrating both the voice and data services to a new service provider?  Can the service provider deliver both voice and data services to all my offices?

In the end, it seems tightly bundled SIP trunks are best suited to greenfield deployments within the service provider's area of coverage.

The opposite of the above separates the SIP trunks from the broadband delivery to the customers site.  In this case, SIP trunks are a service that the customer uses on their existing or upgraded broadband facilities.  Thus the term Bring Your Own BroadBand (or BYOBB) was born.

The advantages of this service offering is that it can be offered virtually everywhere where there is sufficient broadband and it can be layered on top of existing Internet services. This allows an enterprise to partially or fully migrate to SIP trunking without disrupting their current data services.  For some enterprises, they have already done extensive upgrades to their data infrastructure and SIP trunking is just another application that was already budgeted for well in advance.  The ability to choose multiple SIP trunking services separately from the broadband is a powerful tool when negotiating on a service contract, especially when looking for local numbers outside the US.

Many of the BYOBB SIP trunking service providers let you choose the equipment at your premise.  From WAN access, the router, security solution and the media gateway.

On the downside, I've heard some debate about the validity of the methods used to test the existing broadband circuits and how to prove compliance with service level agreement terms, especially with voice quality.  Then there is a long-term problem of the broadband carrier managing the traffic inside their network.   If it works today, will it work tomorrow as they add new customers? It's important to choose a service provider that supports built-in quality monitoring capabilities, including RTCP-XR which reports real-time R factor scores on voice quality.

Can You Have your Cake and Eat it too?
There are a number SIP trunking service providers that try to ride the fence and will offer you either a bundled service or unbundled, based on your individual situation.  However, it sounds like you will get pressured hard to take the bundled service to control quality and "maximize value".  The bundled services are frequently wrapped up in one-size-fits-all packages that are a lot easier for them to sell, install and service.  The only question is:  Do you fit the one size they are offering?

What's Right for You?
Well, it really depends on a few factors:
  1. How much do you value having "one throat to choke"?
  2. How much bandwidth do you currently have and is it voice-ready?  If you already have a good broadband provider, use it!  If not, maybe a bundle would get both upgraded at once for a good price.
  3. Are you under contract with either a voice or data service provider?  Does it make sense to break either or both the contracts?  Work the numbers - then decide.
  4. How much control do you want over the equipment and services?  If you could care less, just go with a bundle.  The more you know, the more control over the services and equipment you will invariably want - go with unbundled services.
  5. Are you planning a slow migration with a few circuits to start or are you going to cut over all at once?  Complex and gradual cut-overs need more control.
Hopefully this background on the range of SIP trunking offerings will help you with your adoption.  Make sure you ask the right questions and consider your individual situation before signing anything!

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