A couple of months after I moved to the US from England, I was sent to New Mexico to work with a small ILEC and I got my first glimpse of the grandeur of the landscapes in the American West. The central office was half-way up a mountain, and over the weekend I was able to visit White Sands National Monument, which was like nothing I’d ever seen.
It’s fair to say that I caught the travel bug. I had a competition with some of my coworkers to see how many states we could visit (I’m up to 45 as I write this), along with some complex rules about what counted as “visiting a state” (staying the night, or visiting a tourist attraction).
I remember wondering if it was possible to travel and work at the same time – and in researching this I came across the term “Digital Nomad”. Digital nomads are people who work online and who don’t really have a permanent home – they just travel all the time.
I never got up the courage to do this myself, but I was fascinated by the idea, and enjoyed learning about the odd complexities of this lifestyle. One of the biggest challenges of being a digital nomad was what to do about your mail. However hard you try, it’s not really possible to be a functional citizen of the US without having a mailing address.
Although these people were trying to live “digital lives” – in the cloud – they still needed to maintain some kind of local physical connection to the real world, so people could communicate with them.
Fast forward to today, and there’s a lot of buzz in the telecoms industry about hosted voice platforms – the idea that an ILEC could replace the class 5 switch in its CO with a hosted voice switch in the cloud. But this idea of hosted voice platforms has the same problem as the digital nomads – you might want all your subscribers to live in the cloud, but how do other local telcos communicate with them? What do we do about all the TDM trunks?
In this article I’ll give a high-level overview of the architecture that is used to support local subscribers and local TDM trunk groups – all while using a hosted voice switch in the cloud.
Hosted Voice for Subscribers
If you start using a hosted voice platform, the primary change is that your subscribers are now configured on the hosted voice switch.
- All your subscribers “live” on the hosted platform, and those subscribers would need to be converted to SIP so that each line can register with the voice platform in the cloud.
- All subscriber features and call services would then be provided by your new hosted voice platform, including UCaaS services for businesses.
This may require you to rethink your access network, as every residential and business line would need to use the SIP protocol, and would be registering over the public internet to a hosted voice platform in the cloud.
SIP trunks to the PSTN
If you have SIP trunks for PSTN connectivity then these can either be moved to connect directly to the hosted voice switch, or in some cases PSTN connectivity via SIP may be provided by the vendor as part of their service.
What about TDM trunks?
Most ILECs still have some SS7/ISUP trunks to the tandem or other local end-offices. How can these be used if the switch is in the cloud?
- Most hosted switch vendors recommend a local media gateway, in your central office, that can terminate those TDM trunks locally.
- This media gateway could potentially be your existing class 5 switch, with no subscribers, but most vendors are recommending that you purchase a media gateway from TelcoBridges. TelcoBridges is a Canadian company that is committed to the media gateway space for the long-haul, so you don’t have to worry about getting a dreaded end-of-life notice for their products.
- The TelcoBridges media gateways can support these ISUP trunks as well as the SS7 links, and then pass that traffic over a SIP trunk to the cloud-hosted voice platform.
I’m not a regulatory expert, but regardless of the TDM trunks, it’s my understanding that there are NECA requirements that mandate a media gateway in your own LATA. I’ve heard a variety of interpretations for exactly what that means, so you would want to discuss with your regulatory consultant when making a decision. Regardless of the details, the media gateway would be a necessary step in fulfilling those requirements.
Hosted Voice Switch Architecture
Let’s put all that together with a diagram. The key here is that your subscribers connect directly to the hosted voice switch, your TDM trunks connect to the local media gateway, and there’s an “internal” SIP trunk between your two platforms.
What’s next?
This is the first in a series of four articles we’ll be publishing in the next few weeks exploring the idea of hosted voice platforms in more detail. In the upcoming articles we’ll be discussing the pros and cons of moving in this direction, along with our overall assessment of the options and how we can help you out if you do want to explore this in more detail.
If you can’t wait, feel free to reach out now to discuss your particular situation. Also please note that we have a partnership with TelcoBridges, so if you ever want advice about their media gateways, or are considering a purchase, please let us know and we’d be happy to guide you through that.
