Unfortunately, you cannot enter an international phone number on your U.S. tax return. In order to complete and e-file your return, you can enter the phone number of a relative or friend in the U.S, or a "dummy number" (800-555-1212). Your entry will be identified as a placeholder number and if the IRS has any questions, they will reach out to you via mail.
The IRS asks for your phone number in case they have a question about your return (this is rare). They will not, however, call an international phone number.
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