Why not require a non-voip phone number instead of passport?
SIM cards are as cheap as £1 where I live. £1 per account is nothing and I wouldn't be surprised if there are ways to get unique numbers for even less.
alt Hacker News
SIM cards are as cheap as £1 where I live. £1 per account is nothing and I wouldn't be surprised if there are ways to get unique numbers for even less.