Then go get in touch with them. Who knows what'll happen.
Discussion
The biggest challenge I find these days is I am not a fan of the mega popular ones like whatsapp, discord, and telegram for privacy and security reasons.
I miss the days when IRC was still popular. I would still be rocking it if people knew what it was and would be willing to use it with me.
I sometimes use matrix, but I rarely go on there anymore.
Doesn't https://nostrnests.com/ have voice chat? I haven't tried it, other than that it's a pickle, the other one I can think would suit you is XMPP's voice chat, but I haven't got it to reliably work, and I doubt you could get more people on it, it really sucks when there is so much people on the big tech side of the internet.
No voice chat. Too private for that. Real time text communications only.
I've used XMPP before for text chat. It was alright, but I just kept thinking why don't I just use IRC lol.
I had the same problem with XMPP, and the OMEMO convinced me to make the switch, that and I remember reading the RFCs and liking some of them, but it really subjective.
You can always try Chachi and invite people (I've no idea how it works), now that I think about it I haven't tried Chachi either, I really need to get back to testing all the apps, they're all really cool.