I've been experiencing a sort of volume control problem with my 8900. During calls the phone will turn the volume up and down abruptly or kick off (as if other caller was on mute for a split second.) When this occurs on speaker phone it will automatically go into handheld mode. The problem started when a black box with plus signs (+) lined diagonally across it showed up on the call screen. The phone has continued this trend regardless of whether or not the "plus" box is there. I cannot find the icon/emblem anywhere in the manual. Any insight would be greatly appreciated.
