BVoIP has developed custom Cisco 7940 / 7960 phone templates that are available to use for BVoIP Partners.
The difference between the customized templates that we created by BVoIP and the original 3CX developed templates are that the phones can connect back to the phone system without the need for an on-prem proxy or SBC (Session Border Controller).
Instead, the templates are designed to use the BVoIP Server Side SBC.
That means the phones can simply be plugged in behind a router and "phone home" without any outside intervention.
That also means you can take a phone and move it easily from any internet connection / network without reconfiguration of the devices.
If you are a BVoIP partner you can submit a request for access.