BB7520 and Bluetooth
Since the original thread was lost...
There is an echo issue with BB7520 with os4.0 and bluetooth. On most all headsets, when the volume is above 50-60% you will get a noticealbe echo from your own voice. This is avoidable by keeping the volume at lower levels whenever possible (this can be assisted by your choice of headset--those with speakers inside the ear canal will help more). So far in my personal quest for a bluetooth headset, I have tried the BlueTrek G2, the Bluespoon AX, the Motorola HS-810 and the 820, and the Jabra BT250. The one I am going to stick with is the Jabra BT250. I find it to be overall more comfortable than the others, and the fact that the speaker is inside the ear canal helps with keeping to volume low to avoid echo. I do wish that the Jabra was able to cancel a little bit more background noise, but that really isn't as much of an issue as the background noise with the Bluespoon or the HS-820.