That looks like a very difficult area, not really much VoIP availability. The local phone "switch" is served only by Telebec and their mobility division.
You might try to ask some of these folks:
»
www.voicemeup.com/covera ··· _code_PQ»
www.acrovoice.ca/content/contactRemember, your parents can sign up with pretty much anyone and make outbound calls.
The only issue is the inbound number (DID). They might be able to get an inbound number in a nearby larger town.