Try Magic Jack.
http://magicjackcanada.com/shop/
I bought one at Best Buy a few weeks ago. It's $10/
year for a "403" number and that includes caller ID and voicemail. It's unreal. I haven't had anybody complain about the call quality yet and it sounds perfect on my end. I use my same cordless phones throughout the house that I used to use with my Telus landline.
I don't know if you can keep your existing number.