Please read the following information regarding 3CX on Linux:
Supported VM Platforms
3CX Phone System is extensively tested to be run as a VM which eliminates the cost of separate hardware and adds high availability solutions based on the hypervisor infrastructure. Tested and supported hypervisor platforms are:
VMware ESX 5.X and above.
Microsoft HyperV 2008 R2 and above. See our Hyper-V Page for the specific settings for running 3CX.
KVM
Citrix XenServer 7.0 and above
Amazon AWS
Google Cloud Engine Instance
Avoid using 3CX Phone System on converted VMs (P2V) because a converted virtual machine might have timing issues, which causes the guest operating system not to sync with the timer of the hypervisor.