[maze]

Check your settings for Activesync (If using Exchange) and if your Email accounts are automatically downloading your mail. I live in a non-EVDO area, so if Activesync is performing a "heartbeat" then a call will go straight to voicemail. In fact, all data in a 1X network will send calls to voicemail.

Also, I finally figured out that I was setting my ringer volume incorrectly... I was just using the volume control from the today screen to go up and down. When you do that, only the volume control on the right moves up/down, you need to use your finger/stylus and adjust the control on the left in order for the ringer volume to go up.