The only "true" random number generators are they made on hardware, using signal/noise that cant be predicted (yet).
One could argue that as soon as it can be predicted, it's not random anymore. As soon as the signal/noise you're talking about can be predicted, those random numbers will become nothing but pseudo-random numbers.
Entropic sources are right now an excellent basis for random numbers, but that's only based on the fact that there are so many factors involved that it is too hard to predict it. And as soon as they become predictable (not likely to happen very soon, but possible), there goes your randomness.

Compare it to rolling the dice. Most people would say that that's completely random, but I don't think so: if you take into consideration gravity, the movement of the solar system, the movement of the person throwing the dice, the bounce-factor of the table, the hardness of the dice, wind, and billions of other factors (I guess you could say that the breathing of every single person on this earth manipulates how the dice roll) you don't have randomness anymore.

I don't even believe that there is one source out there that can be called completely random.