A method and an apparatus provide for determining whether a data terminal equipment (DTE) device represents a compatible device lacking an independent power supply and adapted to be powered using phantom power over a wired connection from a communications device such as a switch. A detection signal may...http://www.google.com.tw/patents/US6804351?utm_source=gb-gplus-share專利 US6804351 - Method and apparatus for detecting a compatible phantom powered device using common mode signaling
