When in the field one of the key components of the battle is communication. Without communication no one will know the full situation and chaos will ensue. In the Military it is standard for there to only be one or two radio operators per squad. In airsoft it really is up to the needs of the squad.
It would be beneficial for there to be one radio between every two people, then if one radio operator in a fire team is down there is still another operator up to call in contact without having to take the radio from the downed teammate. Another benefit of a radio between every two people is that it allows a team to split in to two man recon pairs and spread out while still maintaining communication.
It is important to not become too dependent on the radio as radios tend to be fairly loud. Even if a head set is used to reduce noise, traffic can still be heard by the enemy from the speaking member by the team. Your team should work on using hand and arm signals, and whistles for communication when in closer proximity. Hand and arm signals are good for patrolling as they require no noise but require movement that could be seen by the enemy. Whistles are good to use while dug in and defending a position as you are able to notifying your teammates that you have the enemy in sight with no movement. It does require noise but whistles can be trained to sound like natural sounds of birds and wind. However you still run the risk of the enemy hearing the whistle and giving your location away. This might be a necessary risk as drawing the attention of the enemy will allow for your teammates to move to a better flanking position and hit the enemy.
Whichever form of communication you use, or combination of forms, make sure that the entire squad is fully trained. Make sure that everyone knows what each signal means, and which form of communication to use in specific situations.