A first communication device that is connectable to a second communication device. The first communication device includes a negotiation data transmitter that transmits negotiation data with a first group of frequencies to the second communication device. The first communication device includes a negotiation...http://www.google.com.hk/patents/US6987802?utm_source=gb-gplus-share專利 US6987802 - Activation of multiple XDSL modems with implicit channel probe
