Telecoms cloud for unified communications, powered by Virtuozzo
Wherever you look there are products and services running on Virtuozzo cloud – but it is not always obvious just what is under the hood. We talked with Vincent Suurenbroek and Sven Witlox to learn about a cloud-based VoIP project in The Netherlands.
Vincent is co-founder of Dutch cloud hosting provider, H4Hosting. Sven, a telecoms engineer with more than two decades of experience, is the founder of Mister VoIP, offering managed communications services to businesses in The Netherlands.
There’s a case study here, but the guys had plenty more to say, so here’s the full Q&A!


Vincent, give us a short history of H4Hosting?
Like Sven I also have a background in VoIP – a company called i4IP, which is now part of the UCaaS suite at Enreach. When we were running our VoIP company we needed a way to host our products – this was back in the 2010s – and we met a company called OnApp at a telco event, here in the Netherlands. This started our journey as a cloud/hosting provider.
Today we have three datacenters, provide colo, IP transit, VPS and custom cloud solutions, and use Virtuozzo Hybrid Infrastructure as the underlying cloud platform.
What makes you special - why does H4Hosting exist?
We create bespoke hosting solutions, and we specialize in cloud and connectivity for applications and use cases that need very low latency – such as VoIP and unified communications, TV and streaming media.
We have a big presence at the media park in Hilversum, and our own fiber network on that campus, with links into the major backbones in The Netherlands. For these latency sensitive cases, we understand that IaaS is only part of the chain, and solve the connectivity side of things for customers too.


Sven, let’s get a quick intro to Mister VoIP
Sure! I started the company about four years ago, during Covid. There was obviously a sudden, urgent need for businesses to switch to remote working, and that’s the solution Mister VoIP was set up to provide – remote telephony, unified communications.
We use a product called 3CX – if you’re not familiar with the unified comms space, it’s a bit like Teams, but with much more advanced telephony, CRM integration, lots of features for seamless landline and mobile communications.
It’s used by some very large global companies, and 3CX provides various cloud options too with AWS, GCP and so on. But, they are a bit limited in terms of customization – so we provide a fully managed bespoke 3CX based service, in the cloud.
Now that the pandemic is hopefully a thing of the past, is there still a strong market?
At the time people asked me, WHY are you doing this? Are you mad? But there is still very strong demand. Most of our customers are here in The Netherlands, and in this country telephone is still the way you do business. Yes, there is Teams and Zoom and so on, but people like to make actual phone calls to get things done.
As a start-up we grew fast to 100 customers and we are still onboarding at a rapid pace – 8 new customers just last week – and now we’re hiring to continue that growth. We’re a Silver 3CX Partner today, and hope to reach Gold status next year.
What’s unique about Mister VoIP? Apart from the name…
This isn’t a unique product: you can get VoIP from lots of providers, including the large telcos like KPN, and 3CX is available from resellers everywhere. So what we focus on is the local service. It’s all cloud-based, all included in a single subscription – advice, cloud-based 3CX, SIP trunk, phone numbers, updates – all included. Local support with same day fix, all included. Need us to integrate 3CX with your CRM? No problem. So we’re like KPN, except… good service.
Vincent, what was the trigger for H4Hosting to switch to Virtuozzo Hybrid Infrastructure?
We ran services on OnApp for many years, and OnApp is now part of Virtuozzo of course. There were various reasons to make the switch. We wanted Virtuozzo’s more robust storage, better cluster orchestration, easier networking, and more resilient architecture overall. Plus with CentOS 7 reaching End of Life, that was another trigger. I’m in love with Virtuozzo Hybrid Infrastructure, or VHI as we call it. It makes life easier for us, and makes cloud easy for our customers too.
And how was the migration process to Virtuozzo Hybrid Infrastructure?
Migration is never something you can take lightly, especially as we had a few thousand users on our OnApp infrastructure. And, when you’re providing telecoms infrastructure, well – obviously you have to be especially careful. There are warm and cold migration options, but given that we were running PBXs on a stack based on CentOS 7, we took the safest route with cold migration.
The Virtuozzo team provided great support. I give them a hard time but they know their stuff, the knowledge and service is good, and migration scripts from OnApp to VHI were pretty seamless. Ok, we found a few undocumented features but worked through them together – migration is never a 100% simple process. It was pretty painless overall.
Sven, why did you choose H4Hosting?
Having a local infrastructure partner is very important. It minimizes latency, gives us a local relationship, and means we get an instant response at all hours. If we have issues, they are fixed, no problem. As Vincent said, the connectivity is crucial. If you’re hosting a website, the user can put up with a delay while the page loads. For voice calls, you cannot tolerate latency or any jitter in the connection. The H4 service is designed for this kind of use case – it’s perfect.
And how does H4Hosting / Virtuozzo cloud benefit Mister VoIP customers?
Our customers don’t see the infrastructure, they don’t see Virtuozzo: that’s kind of the point, this is VoIP as a Service. Most customers don’t even see 3CX, we just manage the whole thing for them, though if your IT team wants admin access we can do that of course.
So really, there are two benefits of the infrastructure. First is the reliability of the hosted 3CX instance and the connectivity from H4Hosting. Customers expect perfect voice calls, and that’s what they get. The infrastructure is invisible to them, as it should be.
Second is how fast a customer can go from meeting Mister VoIP to using the service. I get a self-service portal and a pool of private cloud resources, with pre-configured VM flavors to suit different sizes of customer. It takes a couple of minutes to configure the correct virtualized environment for a customer with 4 seats, or 400. Networking is especially easy, and this is critical – giving a unique IP to each instance, it’s just easy.
Then we SSH into the VM, install 3CX, configure the service for the customer’s specific need… it’s very quick to onboard a new client. I love it!
More information…
For high-performance cloud and connectivity, discover H4 Hosting at
https://www.h4hosting.eu
Learn more about Mister VoIP managed cloud-based telephony at
https://www.mister-voip.nl
For more information about Virtuozzo Hybrid Infrastructure, the business-ready OpenStack cloud platform, visit
https://www.virtuozzo.com/hybrid-infrastructure





