I find it super strange that there is no popular offline walkie talkie app for mobile devices. It could be really handy when you are biking with someone for a long distance! You could talk with your friends all the way without any problem. And the best part is that it is free because you will use local network Wifi, or bluetooth.
I have been searching for quite some time and the only app I found was Intercom. It does exactly what I need, provides an easy way to communicate without an internet. But the problem is that it is super glitchy! It can just stop receiving and transferring voice. If you use headset which could be really cool when it is loud on the road, like it usually is, it just does not use headsets. And so on. Very bad...
So the question remains! How to communicate with friends when you are on a ride?