[The Milk Man 09]

Nope it just basically turns on free reign mode, Id say to be safe if you dont want to lose any money from deaths or anything just make a game save before doing whatever but it basically pauses the forward progress of the game and keeps you from being bothered when doing your thing. You can still do missions you just wont get more after completing all that are available to you, at least not until turning your phone back on.