[andy]

For local SIMs, I'd be tempted by 01051mobile or Solomo in Germany, and Lebara in Denmark. Or maybe there will be more by then

Calls to each other at 9 or 5 eurocents and direct-dialled to Canada at 5 cents might mean you'd never use all the credit, but as some alternate options are 39 cents on SIMs which cost more to acquire, why worry.