The radio blackout on airlines was only during landing and takeoff and the FAA recently relaxed the ruling to allow you to use electronic devices at any time by leaving it up to the airlines to decide. Most have opted to allow it, as there haven't been any problems that can be traced back to their usage onboard.
And, if you thought that everyone onboard followed the rule and actually turned everything off like they were supposed to before, I've got a bridge to sell you!