I have been having this problem for some time now. My droid will randomly not register that someone is calling me. My girlfriend has tried to cal me multiple times where my phone does not ring and I get no indication of a missed call. For her it simply acts as if I am not answering my phone and sends her to voicemail after a little bit. (I do get a notification of a new voicemail if she leaves one). I do not know if this has happened with any other numbers, but this has happened to her with two different phones (one an lg then a samsung after she upgraded). Has anyone else heard of a problem like this?