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.
If you have a Canadian or US phone number, make sure you are only typing it in using numbers - no special characters or spaces. There should be total of 3 numbers in the first box and 7 numbers in the second box. You may want to select and delete everything in each box before retyping, just in case there is a hidden space causing the problem. You can also leave the phone number space blank, as it is not a mandatory field.