Available only for desktop users for now, the new Push-to-talk feature offers a new effortless way to communicate: simply press a button for hands-free, instant, and convenient audio messaging. It’s like in the olden days of gaming when gamers would key bind the Push to talk feature to be able to talk when necessary.
You can spin up your own mumble server. It's not that hard, and then once you have that running, you just tell your friends to download the mobile client and boom. You're done