The built-in Jitsi integration lets you create a voice chat call via a single button click. You can also put those call links in a channel description if you like.

We do have plans to make the integration offer some additional ways to jump into a call, and have been talking about adding video chat. But our focus has been on building the best text chat possible, given there are multiple actively developed FOSS video call systems that we can integrate with.

Looks like it has integration with Jitsi Meet https://zulip.com/integrations/jitsi