I did what PX Eliezer suggested when I was looking for a new phone provider to replace Bell Canada. Before I made the switch I set up an account with Voip.ms and got a DID for 98 cents a month. I tried it for a few months, setting up my ATA and making tweaks here and there until I was satisfied that it was a service capable of replacing POTS for my needs. During the time I was trying out the voip service I kept my Bell service. When I felt I was ready to make the switch I kept the original DID and also had my existing phone number ported over to become a second DID. I use the original DID for experimenting and have it set up so that I can call it from my cell and basically get mobile long distance at a tiny fraction of the mobile providers price. I found this way to be less stressful since I didn't have to worry about having all the equipment and the voip service setup right away as soon as a port over would happen. I could take my time and read (many helpful people here with great posts) and tinker and learn and still use the POTS until I made the switch over.