Privacy major issue

Even when opting for standalone storage (on your own WP server), this plugin communicates with 3CX servers by WebSockets for real-time operations. And all your confidential data are passed through this channel and come to C3X servers without encryption: visitor informations such as name or email address, and every message you or your visitor can send. The “enable encryption” option within the WP plugin has no effect on it.
The data are encrypted in transit (WSS protocol) but can be read on 3CX servers. We find the mention

Chat message content is not logged

on the “external party services” chapter, but it is very unclear that these external services are used even if you choose the standalone setup.
It means for me a major privacy issue, a poor GDPR compliance and, overall, a severe lack of trustability for a solution presented as standalone.