An applications asks user to provide a phone number. When the number is wrong, the application displays a message. There can be two cases:
1) the phone is correct, but another user already used it for registration; 2) the phone is incorrect (has wrong format).
Is it correct to say:
1) "This phone number is used by another user. Please provide a different one". 2) "Invalid phone number. Please check and try again.".
Or may be there is a better way to write these messages?