This mod now requires Shine's basecommands plugin to be loaded.
A mod that allows all players to talk to players in their proximity.
There's lots of mods like this on the workshop, although none are as complete and as bug-free as this.
First of all you have to set your keybindings through the vanilla keybinding menu. It's at the very bottom of the list, called something like "Proximity Chat". Once you've set your keybindings, you can use proximity/local voice chat on any server that has this mod enabled.
If you think the default colors are ugly, you can change them through the HUD menu of NS2+ settings, at the very bottom.
Spectators can only use local voice chat when the game is not in progress, and even then, only when in first person mode! This is a technical limitation, although I could work around it, but I'm too lazy.
Commanders can only use team-only local voice chat, and can not hear voice chat from enemies that he can not see either (obviously). The reason for the team-only restriction is also due to technical limitations.