Please allow for calls to be disabled, either for the entire server or on a per-room basis

[robin24]

While setting up my own Synapse server, I wanted to disable all call-related features as the community I'm building this for uses a different, already existing platform for voice chats.
When I failed to find anything related in the docs, I decided to take a look at the Element-Web config options and added the following to my config:

"setting_defaults": {
"UIFeature.voip": false,
}

As it turns out, however, this setting only applies to Element-Web, not to the various client apps which are still able to initiate and accept calls as before, this was also confirmed in the related issue I filed against Element-iOS.

For my community setup, I feel that given the inability to disable this somewhat forces me into supporting the feature, which includes setting up a TUN server as otherwise calls will appear to work and then fail to establish probably resulting in unnecessary support overhead.

I do want to say that I really appreciate the fact that Matrix does have built-in VOIP support (I've used it on other servers and it works great), but I feel that as a server admin I should be able to control whether or not this is available on my instance.

I therefore would like to suggest the following:

• homeserver.yaml options to disable 1:1 and conference calls
• Since conference calls are by default handled by an externally hosted Jitsi server, they should be off by default for privacy reasons
• There should be a configurable power level for who can start a conference in a room - this already appears to be restricted to moderators by default, but it would be nice to add more flexibility here so that this could either be restricted to admins, or all users could be given this ability in certain dedicated rooms on the server
• There should be API endpoints for Matrix clients to query whether or not calling is supported, so that the UI can be updated accordingly

I hope that at least some of what I'm proposing can be considered at some point, would really appreciate some more granularity here.

Thanks!