Their help page claims a phone number can be linked to 10 accounts at once, but in practice I've found that limit to be 4 or even less. Also, they often prevent

Their help page claims a phone number can be linked to 10 accounts at once, but in practice I've found that limit to be 4 or even less. Also, they often prevent a number from being added to more accounts for a few days or weeks even if you remove it from all accounts.