I recently bought a Volla Phone X and tried to use it on the Koodo/Telus network here in Canada.
Text messaging, and also email and web browsing, worked satisfactorily on their 4th generation network, but the voice service did not. Technical Support did not provide any real technical support. (This may be typical, but the Koodo/Telus store they directed me to tried a lot harder).
I was confident that the phone was not faulty and was also determined to use it, so after some days of trying to get the problem resolved without success, I walked into a Fido/Rogers store. I requested that we use a Test SIM to check that the Phone X would work fully and it did.
I believe that the success is simply due to the signalling frequencies the Fido/Rogers network use.
I have not tried it with a Bell network or Freedom/Shaw network so if there are customers in Canada using these last two networks they will be helping any future Canadian customers of the Volla by confirming that there are other options besides Fido/Rogers (though I did agree a good deal by Canadian mobile industry standards).
Posting helpful advice regarding which network will support the Volla phone will save a lot of frustration to new customers.