A minor chance. It shouldn't become impossible to have a phone call there. You'd just have to repeat yourself sometimes, or ask the one on the other end to repeat themselves.
For reasons much smaller than, it's a mega-slum. Even topside has places it would likely be impossible to talk.
I don't think making it impossible to talk in busy places should be out of the question.
Nicer phones have much better noise canceling tech. Same with nicer wireless headsets. So, I would say that this should be non-existent on an 11, rarer on a 9, a problem on sevens, and we won't even talk about threes.
Some players already roleplay this out and it's fine like that. My suggestion would be much simpler, a new command for progias to let you describe ambient sounds and play them only for the other person on the call, so people around the person on the phone don't see Joebaka saying "*sounds of an AV engine starting*"
Honking cars and bustling foot traffic? Street. Add in gunshots and screams, Red street.
Clinking glasses, loud and incoherent chatter? Bar. Add in shouting and glass shattering, Red bar.
Piercing wind howls? Badlands.
Water drips, splashes and echoes? Sewers.
*car door slam, engine starting* Gotta jet. Talk soon.
*waves of junk rattling around* Now where did I put it...
Fuck. Off. *loud clattering, then silence*
> Throw progia-7 to E
