I was having issues with incoming and outgoing calls not connecting to the Grandstream. After repeated emails exhanges with tech support I was informed the Granstream does not support more than two phones being connected AND they have to be connected directly ... I cannot use the house wiring, really?! So I came on this forum and found this post. I purchased a OBI-100 (which explicitly says it DOES support house wiring), configured it in a matter of minutes to work with VOIPo and the quality is GREAT. No dropped call, no missed connections, and I would suggest the OBI-100 to anyone.