Being a truck driver, I tested the MX150 and the MX500, which I bought at the same time. 2 out of 2 other truck driving buddies rated the MX150 better at sound quality on their end of the line. Less "running water" in the background sounds.I could hear equally as well on either set. I have learned however, that if the other person has to "work" at hearing you, they'll probably hang up. The MX500 works well at home with the cordless.