It does a great job of amplifying two-way conversations. The problem is that it has no "off" switch--it turns itself off when it doesn't detect sound. So, if you're having a conversation with someone who is a soft speaker (the main reason I bought the thing!) it turns off--and then you hear even less than without it. So I find myself clearing my throat a lot, just to keep it turned on. It's especially disconcerting when on hold--you can't tell if you're still connected.