Apple users can check in their App Store for DriveSocial, coming soon.

Zello https://apps.apple.com/us/app/zello-walkie-talkie/id508231856

Android users can find them here:

DriveSocial https://play.google.com/store/apps/details?id=io.drivesocial.android.app&hl=en_US 

Zello https://play.google.com/store/apps/details?id=com.loudtalks&hl=en_US 

On both apps, look for and join the U4RYDE group. Here is a handy link for Zello:

Zello http://www.zello.com/U4RYDE