I have some great news for folks with a 7520 (and Nextel network). I tried a couple different brand BT headsets and could not get rid of the echo with the 7520. I finally settled on the H700, despite the echo still persisting, and started getting used to it. Well, I just applied the 4.1 update and the echo is GONE - I cannot hear my own voice at all. Looks like the BT sync improvement wasn't the only improvement to bluetooth with this update. Another great improvement with 4.1 is the addition of MMS capability... hopefully text follows suit.