I agree with Dameon on his frustration with VoIP/SIP phones but for different reasons. Every device requires a "genius" or IT type person to configure easily.
Even those with a Web interface. Someone needs to design a wizard like we have for Truphone on the Nokia handsets, but for desk VoIP phones that says:
1. Connect phone to your router for an IP connection
2. Identify your IP address (internal)
3. Press Configure
Until that happens the IP phones will always play second fiddle to analog telephone adapters and analog handsets in any location where the GEEK is not in residence full time or on call.