Bike to bike communications can be achieved by one of three ways:1. Using long range Bluetooth full-duplex systems such as Sena, Cardo Scala and others.
Simple to set up but generally does not allow you to talk to more than one or two bikes at a time. Not suitable for large groups.
Ranges claimed are strictly line-of-sight, with NO obstructions in the way and cannot be achieved in urban areas except on very straight roads.
Easily paired to Phones, GPS and MP3 players. Ideal for rider-pillion without wires.
2. Using Two-way radio using Push-to-talk.
A little more kit to set up but at the press of a handle bar mounted button any number of riders with compatible radios can hear you. Ideal for fast group comms.
Range is much better, much better in urban areas and not strictly line-of-sight.
Wired and almost-wireless systems are available.
The best of both worlds can be had by combining a Bluetooth system with a radio system using a Bluetooth radio interface such as the Sena SR10. This will give you long range bike-to-bike group communications as well as wireless rider-pillion, entertainment, phone and Sat-Nav guidance.