Has anyone tested a USB Mic or headset? Maybe one of those cell phone USB headsets? I was thinking of picking up one of these units and was surprised to find NO MIC! Might be worthwhile if someone has one of these cell phone USB or other headset that they can test with, and post results here. If there is a possibility of a USB Mic, or USB headset, has anyone had success with a SIP softphone to connect to an Asterisk server?