I've had a couple of people bring this up, and even disagree with me.

For an overview of the Talkspot and UNO service, take a look at my overview here.

For Rogers' Talkspot and Fido's UNO service (which use the exact same technology), you do require a special phone that has Wifi built into it.

For Fido, there's only one phone available that works on their UNO service, the Nokia 6301. Now, Nokia does make good phones, but one sized fits all probably doesn't work for most Canadians, but the options should increase over time, this kind of system is the way of the future.

For Rogers' Talkspot, they have several phones available, like the Blackberry Pearl and Nokia 6086, though it must be Rogers branded (no buying them used from people in the USA or anything, ugh)

How They Work & Why You Need a Special Phone for UNO and TalkSpot

The way these devices work is that when they're in-range of your wireless internet router (they prefer you use their voice-optimized router, but that's not a requirement), they use the wireless internet network, rather than the cell phone network to send or receive your call.

So, you need a phone that can communicate over the wireless internet network (ie: wifi) like a laptop can. Most phones aren't built for this, so, you're going to need to give up your old phone, and choose one of their limited options to take advantage of this.

If this isn't an option for you and you want to ditch or don't have a landline, I suggest getting some kind of VoIP solution, at least for your outgoing call, like Skype. So, you can still save a bundle on that end, but it is by no means as seamless as these new services offered by both Rogers and Fido.