Voice communication between two smartphones over Wi-Fi without a hotspot?

Question

Android

I recently got into a situation (we were traveling with a friend in two cars), when there was no cellular network signal, and it was very necessary to talk. What I thought - if there are two smart phones with WiFi, then why not use this communication channel? I don’t ask how to legalize two devices without an access point, it’s probably possible, what’s more interesting is what program can communicate by voice over WiFi without a dedicated server? In a word, something like PTT , but only in full synchronous mode and hands free.
Thank you.

Answer 1

Walkie-talkies met only over gprs, for example zello.com
I agree, it would be great if they could work on wifi.