I assume you are comparing your situation now to a PSTN system where all the phones were wired? Because there is no reason a cordless system would work any differently on VoIP or PSTN. I agree with Russell's suggestion. I have VOIPo feeding into home wiring with two-line jacks throughout the house. I also have a two-line cordless system with six handsets. Even though my ATA is in the basement, the base station for my cordless system is on the second floor where the coverage is better, plugged into a wired jack there. This way, I get cordless reception throughout the house (three storeys plus the basement), and can plug in a corded phone anywhere.