Apparently it is possible to e-file with TurboTax when you have a foreign postal address but can only input a US phone number. Why is this so?

[Cindy0H]

The IRS will not call an international phone number.

You can enter the phone number of a relative or friend in the U.S. or a "dummy number" (800-555-1212). This will allow you to complete your return, and the IRS will identify your entry as a placeholder number - if they have questions, they will mail them to you.