The error message may not be helpful but it also is worded to stop attackers from narrowing down the possible phone numbers to use. ex. they tell you the numbe

The error message may not be helpful but it also is worded to stop attackers from narrowing down the possible phone numbers to use. ex. they tell you the number starts with a 9. The attacker cuts the number of phone numbers to try in a brute force attempt. Yes, there are better ways to do this but this method works to an extent and for most people it is quite easy to remember their phone number.