Chapter 4: Symfony (1.x): Phone "1234567900" is not an integer.
sfValidatorInteger needs to change to sfValidatorNumber in BaseAddressForm.class.php so that a standard 10-digit phone number can be validated.
That will make the error message go away at any rate. But doesn't address the root cause which is how Symfony/PHP handles long integers.
Having to do this is a pain though since it's an auto-generated file.