I would like to use turbotax as a non-resident. How can I enter an international phone number to the contact details (otherwise I can not procede)?

TurboTax won’t allow you to input anything other than a Canadian or US phone number. If you have a phone number from another country, just don’t include it. The CRA will contact you by mail.

When I left the field open, I could not procede. I now put a number without country code. Hope that does not lead to any confusion...