Aatrox Communications recently worked with a partner on a 3CX deployment, and we wanted to take the time to give a bit of detail on best-practice VoIP infrastructure.

3CX can be deployed in a number of different ways. Choosing the right method to use can be tricky, and is generally dependent on the customer’s infrastructure.

It’s important to spend the time to understand how different deployment models vary in terms of ongoing maintenance requirements and the initial deployment cost.


For this 3CX deployment, the customer wanted 40 x Yealink T52 IP Phones and 5 x Yealink CP960 conference phones.

The customer already had infrastructure in Microsoft Azure, with an MPLS network connecting 2 physical sites and Azure via an ExpressRoute. A 3rd physical site was connected via a Site to Site VPN.

This network topology means that all 4 locations (the 3 sites and Azure) are able to communicate locally, without any public internet traversal or address translation via NAT.

MPLS Connections 3CX
Because any on-site handsets can connect to an Azure locally, the optimal location to deploy the 3CX server was in Azure – in this case, a Linux 32 Concurrent Call Virtual Machine.

Capacity planning demonstrated that a DS2 v2 instance was appropriate (2 vCPUs and 7GB of RAM) for standard 3CX usage, as well as call recording and web meeting (which are much more resource intensive than the other PABX roles).

Our partner ordered the phones from their wholesale supplier, and requested all MAC addresses to be supplied in a CSV, with delivery directly to the customer sites. We helped the partner import the CSV of MAC addresses when creating the extensions to allow for easy deployment.


The next step was to enable DHCP option 66 on the DHCP server for each site (several are used).


This allowed our partner to save a great deal of time on deployment, as phones simply needed to be plugged in to get power and network connectivity, and then automatically retrieve the provisioning URL from the DHCP.


The auto-provisioning process allows the handset to download all the configured settings from the 3CX server, and be fully usable without any further configuration.


If managed correctly, a 3CX deployment doesn’t need to be a manual a time-consuming process.


3CX have built some great features into their product to streamline the process – and the partner we worked with here was able to use them effectively to make this a successful and profitable 3CX deployment.
We look forward to working with partners on other deployments such as these.

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