To access F.R.N. using your mobile or tablet download the correct program for your phone/tablet (Android/IOS) from http://www.zello.com, click Free download and select your required system.
E.G. iTunes for IOS
E.G. Google Play for Android
Install your app then to find a channel to use click the search button and enter some text.
You are free to use any server you wish on the Free Radio Network.
Listed below are 4 of the listed UK servers, type your preferred server name into the search box to connect and follow the on-screen instructions.
You can connect to however many servers you wish.