I'm having the same issue! I'm based in Japan and I get that message no matter what. I even tried using the US number of two different relatives. I tried using the area code for America +1, and I tried without it. I tried with a Japanese number, also with and without the Japanese area code. Nothing worked! I was told I needed to change my mailing address to an American one, so I used my PO box but it didn't work. I don't even know why they would suggest that? Please help! TurboTax this is clearly a big issue!!
