Best Practices and Network Design for Cloud PBX

Cloud based IP-PBX phone solutionsHosted VoIP services or hosted PBX services are terms used to describe a cloud-based IP-PBX phone solution that is managed by a service provider. Business can also host their own cloud PBX and internally manage the cloud based PBX. With a cloud PBX approach, there will still be SIP trunks provided by a SIP service provider that communicates with your cloud PBX. In both the hosted PBX and cloud PBX options, a business branch office can plug IP phones into their local LAN and if the VoIP phones that connect to the IP-PBX over the WAN network of the business. Both options enable a business office to have a professional phone system up and running very quickly. Since the VoIP SIP trunk service is hosted, it also provides cost savings and operational advantages.

We compared Hosted VoIP (hosted PBX) vs on-premise VoIP (on-premise PBX) in our earlier blog post.

Perhaps you’re not yet sold on a hosted PBX solution and yet do not prefer any PBX equipment in your office. Then the self managed cloud PBX is the way to go. Here are a few things to consider in your decision process between self-hosted cloud PBX, hosted PBX and on premises PBX solutions:

  • Installation and maintenance
    • Premises-based model – your team is on the hook for procuring, installing and maintaining the hardware and software used to provide the service. Everything related to the service, from cabling to call and session management, from voice quality management to voicemail and dialing features, are all your choice, and your responsibility.
    • Self hosted cloud PBX model – the cloud PBX can be initiated in the cloud with a few clicks. This provides a cloud native and hardware-free PBX solution. The cloud PBX can be easily upgraded and replaced like any other cloud software. Your team will still be responsible to configure the PBX.
    • Hosted model – installation and maintenance of the system is handled by the VoIP service provider, and all you typically have to do is indicate which features you want enabled. Other than that, all hardware and software upgrades, all maintenance activities, and all support requests are handled by the provider.
  • Scalability and VoIP systems
    • This is usually where hosted VoIP solutions shine over cloud PBX and on-premise PBX. Because the systems are hosted by a provider that builds to scale to support all of its customers, hosted VoIP platforms are typically much more scalable than self-hosted solutions, both in terms of capacity and time to implement. Hosted VoIP systems are usually part of a much larger collective platform, which means that resources can be shifted as needed to meet business needs, much more quickly than internally supported systems.
  • Agility and flexibility
    • While maintaining a premises-based VoIP system does allow you full and complete control over the system, implementing changes and incorporating new features can be tricky, time-consuming, and error-prone.
    • Self hosted cloud PBX option provides a nice medium where you do not need to deal with any hardware and you have the flexibility of using widely available and widely supported asterisks based IPPBX systems. As an example, a FreePBX image, one of the flavors of Asterisk based PBXs, can be turned up on an AWS server and configured.
    • Hosted VoIP typically is much quicker to install since the provider should have a full suite of advanced capabilities that can be turned on (instantly) when needed by the company as it grows. The shortcoming is the lack of flexibility in configuration and specific features that your organization may need.
  • Costs
    • Premises-based model – expending capital expenditures (CAPEX) in procuring the hardware and software up front, along with your staff’s time to build the system, or in hiring a third party to do it.
    • In a hosted VoIP model, while there are some installation costs, the real costs come in the operating expenditures (OPEX) that pay the monthly fees.
    • Self hosted cloud PBX will provide the best cost as you both are avoiding any hardware CAPEX and also eliminating the service provider markup for the PBX service.
  • Quality of Voice
    • Traditionally, POTS (Plain Old Telephone Service) lines have been providing better quality over IP based VoIP systems. POTS will only be available for a on premise PBX solution. However with the invent of broadband bonding technologies, VoIP can match the QoS of POTS. Both cloud PBX and hosted PBX solutions rely on SIP trunks that utilize IP networks to transmit VoIP packets. Usually the performance bottleneck happens in the connectivity between the office, where the phones reside, and the IPPBX. However fortunately, broadband bonding solutions address that last mile performance.

Network Architecture Considerations

In terms of the architecture, the VoIP phones on the office LAN can be manually and statically configured, but the more common method is for them to get IP addresses from a DHCP server automatically. Your office gateway will be entered as the “VoIP Gateway” for the phones, so that they know to connect via that gateway IP address when communicating with the outside world, including the mothership PBX.

Your hosted VoIP provider heavily relies on clean and stable WAN connectivity from your office to the cloud PBX they are using. But before we get to that, one very important aspect is your local network. It is advised to have solid LAN wiring and quality LAN switches to support VoIP applications. To be frank, LAN is the easy part of the equation, but nonetheless is sometimes overlooked.

In most cases, you can either procure the IP phones from the hosted VoIP provider, or you may procure them separately – provided they support standard VoIP protocol. We recommend you buy the VoIP phones from your hosted VoIP provider to avoid any configuration related issues. If you are going the cloud PBX self hosted route, you may want to stick with IP phones that are from recognized brands.

For self-hosting your PBX in the cloud, there are quite a few options as the cloud provider as well as options for the cloud PBX. Most cloud PBX options will be a variation of the base asterisk core. The cloud PBX providers will differentiate themselves based on which additional unique features they have added or activated as well as how seamless do they make your installation and maintenance process. As an example, FreePBX can be purchased as an AWS EC2 image with a monthly subscription where you are provided with admin access. As a final piece, you will need to add SIP trunks to your cloud PBX. There are variety of price and quality options for SIP trunks that are also quite cost effective.

If you are going with the hosted PBX, choosing your hosted VoIP provider is also important. Not all service providers are created equal. A good checklist should include the ping times from your location, the fail-over strategies they have on their hosting of the PBXs, and their promised SLAs. Needless to say their pricing structure (per extension, per minute, monthly, annually, etc.) is and should be an important factor. Take into account your growth projections and how your cost will be affected. A good question to ask is if you can transfer your phone numbers when/if you leave that service provider for another hosted VoIP provider. You certainly don’t want to be locked in to a particular provider because your inbound phone numbers are locked down by that provider.

There are many (hundreds of) hosted VoIP providers, but according to PCMag: The Best Business VoIP Providers for 2021 (listed alphabetically) are:

Perhaps one of the most important pillars of your VoIP strategy should be your WAN (Wide Area Network). For WAN connectivity, the traditional approach for professional VoIP service has been heavy investment in an MPLS infrastructure. MPLS is a layer2 network that is usually provided by a single carrier and uses layer2 labels instead of layer3 routing. This provides for extremely fast switching/routing within the MPLS network.

There are several significant downsides of MPLS:

  • Dependency on a single carrier – If the carrier is having network problems, your VoIP system will suffer performance issues or be down altogether.
  • High costs involved both in installation as well as on-going fees
  • Lead times for activating and expanding MPLS
  • Availability – The SLAs promised by MPLS services can be illusive, often promising only to credit the amount prorated by the downtime you experience (which can be negligible compared to the cost of that downtime to your business).

Sample Cloud VoIP/PBX Architecture with SD-WAN

As a real-world example, our company uses an Amazon-hosted FreePBX flavor of the Asterisk solution as the IP-PBX of choice that we host ourselves in AWS, but can be replaced by other flavors of IP-PBX if desired. There may be some confusion about the difference between FreePBX and Asterisk, particularly since they are both free, open source, downloadable communications software. The two leading ones in the world in fact, according to Sangoma Technologies, sponsors and developers of FreePBX. Sangoma describes the differences as follows:

“Asterisk is, in fact, a communications toolkit. Not a ready-to-go PBX. It has a lot of functionality that someone needs to craft into something. That something most often happens to be a PBX, but it doesn’t have to be a PBX. It can be contact center software, an automated call distributor, a voicemail system, a video mail system, an IP-PBX, or so much more. Someone could even add their own IoT hooks to it to turn it into some other kind of communication system

FreePBX, as per the definition from, is “a web-based open source GUI (graphical user interface) that controls and manages Asterisk.” So it’s a GUI built on top of Asterisk that makes it easier to deploy a PBX from that Asterisk core. It’s a complete IP-PBX.”

And now back to your office/business WAN. We mentioned earlier that your PBX heavily relies on clean and stable WAN connectivity from your location to the cloud PBX they are using. In fact, by far the leading cause of poor VoIP performance, from lag time to dropouts to completely dropped calls, is the WAN connection (particularly uplink) from your office to the cloud PBX.

For mission-critical VoIP services, we recommend a multi-WAN strategy where the dependency on ISPs is spread over at least 2, and preferably more providers. A cost-effective SD-WAN capable of broadband bonding VoIP traffic can be used as a gateway for the VoIP/SIP traffic to add high reliability and low latency.

Two of the major factors that increase VoIP reliability are broadband bonding/aggregation (joining multiple Internet lines together for increased bandwidth and reliability), and IP tunneling (creating a dedicated connection between two widely separated points).

In our implementation, all offices (onsite and remote from home) connect to our Broadband Bonding Cloud Relay server using secure broadband bonding IP tunnels for their VoIP traffic. The tunnels that VoIP/SIP traffic goes through are specialized and optimized for VoIP/SIP traffic. The Broadband Bonding Cloud Relay then relays that traffic to/from the IP PBX. Our IP PBX is a cloud-based, Asterisk-based PBX that runs on Amazon EC2. This type of configuration can be used as a high level template for any type of business phone system. All Cloud PBXs use SIP trunks and we are doing the same.


With a VoIP-Aware SD-WAN Solution, Your Cloud IP-PBX Shines

Cloud VoIP/PBX solutions are becoming more and more viable for handling business-critical phone systems. However, the call quality will remain highly dependent on the WAN connections you use to shuffle data back and forth between your offices and your provider.

If you are leveraging modern broadband bonding methods to solidify your Internet connectivity to the cloud, your cloud IP-PBX and VoIP should provide the most robust and highest quality calls, even as individual WAN lines suffer performance fluctuations and outages.

Rob Stone, Mushroom Networks, Inc. 

Mushroom Networks is the provider of Broadband Bonding appliances that put your networks on auto-pilot. Application flows are intelligently routed around network problems such as latency, jitter and packet loss. Network problems are solved even before you can notice.



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