Using the server-side CRM integration is fairly straightforward, but as you have noted it supports a very specific set of capabilities. If you want to take the integration further, there are current options, but those options may be even better with the release of 3CX V18.
3CX has announced a new REST API and Gateway service. While these new tools will not be available (I'm told) with the initial release of V18, I'm hoping for a release of these tools around the December timeframe (just a guess/hunch). While 3CX has not yet outlined what will be possible with the new tools, I'm hopeful that they will expand our integration options going forward.
In the meantime, 3CX provides the Call Control API. We use this API extensively in our solutions. And, at least so far, this API also exists in V18. So, it appears this will continue to be an option in the future. However, 3CX has withdrawn the documentation for this API, presumably in preparation for the release of the new APIs.
Another alternative is the 3CX Phone for Windows Plugin API. Obviously, this has a dependency on using this client, but it makes it easy to respond to events in a more customizable way than is possible with the server-side API. However, I am a little nervous about the latest announcement of an Electron-based desktop client. Will this new client replace 3CX Phone for Windows? Will it support the plugin API? I don't know the answer, but I will try to find out.
The final option would be to use our VoIPTools API. We provide both a REST-based API and a SignalR based API, that allows you to do pretty much anything you want, and it is client agnostic. So, whatever 3CX does in the future, we will have a solution for you.
