Pedrop says:
... How do comms work in this world? ...
TheGenerator says:
... we can use our phones to communicate ...
Pedrop says:
... bluetooth earphones ...
If you can do it with your real phone we can probably do it in-game.
Ear-pieces are probably smaller than we have, and might be more able to be hidden (especially for someone with hair). I think we can say they won't be noticed unless someone specifically looks for them, but unless you take active measures against notice, they will be spotted by someone looking close in an obvious way.
Pedrop says:
... something more cyberpunk-ish - like implanted communicators ...
Maybe not at the start? We can check the book for such Cybernetics, that is probably a thing (though you guys don't have such, yet) or something we can make.
TheGenerator says:
... old FM radio technology ...
Do we want to use such technology for this sort of meeting? Anything out of the ordinary might draw attention.
Someone could just make a call to the others and leave their phone on in their pocket.
The old radio tech could be a backup for if someone notices and objects to the phone.
Someone could also find their way to the roof of a building that overlooks the scene and use a parabolic microphone to listen in. They will be able to observe everything down there, but won't be able to get there very fast. They would be in Rifle Range.