There is no way to do what teams does without significant infrastructure. Same with Slack and others.

If you want something that just gets close to the mark, look at Jitsi. It's about as complete as you could expect for just video/voice.

What you may not understand about conferencing platforms is that they are dozens of different hosted services working together to provide a cohesive UE. Video, SIP, VOIP, auth, identity...these are all separate services that are deployed as microservices to get what you get. If you find the bare minimum of the services you actually need, you can probably cobble something together, but it's not going to be a simple running of one service to get the same experience.

You want either mattermost or the whole matrix stack (backend, plus element with voice/video calls).

Matrix/Element is more of a discord alternative, whereas mattermost tries to be more of a slack alternative, where it seems to have some calendar integrations.

I haven’t tried it myself but Mattermost offers most of what you’re looking for.

https://github.com/mattermost

Check out Big Blue Button - https://demo.bigbluebutton.org/

Their website talks all about using it for teaching students but it's really just like Jitsi with more features.

Jit.si

Matrix with the Jitsi meet plugin.

I think Mattermost is intended to be just that.

I have not tried Matrix yet but I hear it's a good replacement, fashioned more to the likes of Discord but I think it has everything you're looking for

I've been using self-hosted Jitsi Meet for a few weeks now. Works perfectly. Haven't tried the calendar feature, though.

Huly is pretty amazing and has a self host option. It supports chats and video calls, team rooms, and has some cool integration for speech to text note taking. It also functions as a task tracker.

Under super active development right now so host only if you can deal with occasional breaking changes.

Element Server Suite Community https://github.com/element-hq/ess-helm

Jitsi

,but it is a pain in the ass to selfhost with good performance.

You can take a look here as well:

https://github.com/awesome-selfhosted/awesome-selfhosted?tab=readme-ov-file#communication---video-conferencing

One alternative that is not on the awesome selfhosted list is: https://edumeet.org/

But it is even more of a PAIN to selfhost it.

I already made a comment but you should also look at rocketchat and revolt, since they are basically FOSS discord clones

(I saw comments in the thread about wanting audio only calls.)

Anyone know of something that isn't Nextcloud Chat?

Do you absolutely need to put ONE tag on it all and say this is it?

I use jami but i dont think it fits your need for guess links.

Still leave it here just in case

https://jami.net/

Jami is a free/libre, end-to-end encrypted, and private communication software.

If you don't mind seperated tools that do well in their own :

• Zulip for chat
• Jitsi for video meeting
• And whatever calendar you want for the calendar

Vdo.ninja