Thanks for the reply. Even using Cloudflare end to end encryption?You need to setup your system with a custom FQDN and custom SSL certificate.
You cannot just do a CNAME, you'll get SSL errors as the 3CX FQDN only is secured by the automatic Let's Encrypt (which doesn't work with custom FQDN either.)
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.