There is no guarantee that another intelligent life-form would be able to find us. Earth is but a speck of dust in the vastness that is the universe. Also, if they were intelligent, they'd avoid us.
The first is why while I tend to believe that there must be other intelligent life in the universe, I very much doubt that it has ever visited us. You've got the limiting factors on development of intelligent life. Then consider how long such a culture might exist, without destroying itself. On again to whether or not they would develop space travel, let alone something that would make interstellar travel viable. On top of that consider that we've only created an intelligent EM "footprint" that's, at best, something less than a 300 light-year bubble.
300? We weren't emitting radio in the early 1700s! And it will stop soon. We're transitioning to communication methods which don't leave Earth (fibre optics, mainly). It might be that civilisations emit radio signals for a brief blip before developing beyond the need to do so. We're nearly there! If that's the case, the probability in a 13 billion year old galaxy of you listening at exactly the right 50 years are infinitesimally tiny.
Alternatively, there might be billions of subspace messages whizzing past us every second, but we haven't invented a subspace receiver yet, so we can't hear them! Maybe radio is as primitive as smoke signals.
On top of that consider that we've only created an intelligent EM "footprint" that's, at best, something less than a 300 light-year bubble.