CalgaryBen wrote: I'm not familiar with Groundwire, but my preliminary/quick search suggests it might be a viable solution which I'll look into further!
For what it's worth, Groundwire isn't a VoIP service provider. It's a SIP app that allows you to provision any BYOD (Bring Your Own Device or SIP services that aren’t restricted to specific devices or apps) SIP service on it. I would recommend Fongo Mobile (not a BYOD service, in this sense, since it is restricted to a specific app) for use on smartphones before I'd recommend Freephoneline due to the registration interval of 1 hour and, in particular, the potential of a temporary IP ban should a device attempt to register more than 5 times within 5 minutes. Hopefully Fongo Mobile eventually supports Wi-FI/cellular data call handoffs.
Also, Freephone's VoIP Unlock Key (a BYOD service), which one would need to buy in order to use with a smartphone SIP app, costs a one time fee of $89.95+tax, whereas Fongo Mobile is free to use. Freephoneline is mostly intended as a home phone replacement service for use with ATAs and IP Phones, and when used as a home phone replacement service, it's great. There's no better deal, over a long period of time, in Canada for a home phone service.