u can use Virola Messenger self hosted and also public its great supports audio calling screen sharing/remote, file send, groups and all. Just started using it for my company with around 40 pcs and no problem its simple its great recommend it.
Self-Hosted Main
A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.
For Example
- Service: Dropbox - Alternative: Nextcloud
- Service: Google Reader - Alternative: Tiny Tiny RSS
- Service: Blogger - Alternative: WordPress
We welcome posts that include suggestions for good self-hosted alternatives to popular online services, how they are better, or how they give back control of your data. Also include hints and tips for less technical readers.
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nextcloud is really great. you can store files or even video call them in addition to messaging. You can create roles message groups etc
You could probably use rocketchat. It does allow DMs, but there are also rooms you can add everyone to for increased visibility.
I'm not aware of a self-hosted option, but Slack is pretty great as an office IM tool.
Email could also fit this case if you configure it the right way
Matrix/Synapse.
IRC, it's ancient which may sound bad but it means that most implementations have grown mature and won't cause issues.
And plenty of web based clients for it too
I used a $0 tier Slack workspace for this in a small business, it worked OK. The Slack clients are enormous in memory.
We use signal and have a few groups for each category of staff. Super simple, and secure.
No idea of anything already made, but this doesnt sound "way too hard" to code one self if you know how to program.