You may need to disconnect your Telco company's line at the demarc--or make sure power from it is not running to your existing phone jacks. Otherwise, you run this risk of frying your ATA. Visit http://www.voipmyhouse.com/#thesolution.
Also, check out bogolisk and canadaodyowner's pictures/posts over here: merged-freephoneline-ca-free-local-soft ... 21229/331/
Better to ask them about it than me.