Remember: Earth has supported life for 3.5 billion years, but has only supported sentient life for a few million years (counting dolphins), has only had civilization for a few thousand years, and has only had the ability to detect radio signals for a few decades. So even if we do find an inhabited planet, that doesn't mean it's at all likely to have intelligence and radio telescopes. Granted, Alpha Centauri seems to be 2 billion years older than Sol, so any life-bearing planets there could have a considerable headstart; but so far as we know, there's nothing inevitable about the emergence of intelligence or technological civilization, or at least no set timetable for its development.
We like to think about discovering extraterrestrial life in terms of communication and interaction because that's what science fiction has conditioned us to think about, and because it's more satisfying to think about. But realistically it's likely to be more a matter of very long-distance spectroscopy of an alien world's atmosphere and surface, and maybe, if we're ambitious enough, some slower-than-light robot probes which will let our children or grandchildren get a detailed look at whatever's living there.