Just purchased an iphone for my 2006 LS430 and had no problem pairing with my Lexus bluetooth. But there is a loud buzzing sound that lasts a few seconds most of the time when I place a call from the car's touch screen. I brought the car to dealer and we tried to unpair and pair again several times to no avail. I have seen this is a problem for some other Lexus owners. Has anyone found a solution?