Auto formatting breaks character length validation when editing valid content

When adding content, I tried to save the following number into a phone field:

(555) 555-3335 x112

and get the following error:

Registration Phone Number cannot be longer than 16 characters but is currently 19 characters long.

If I change the text of the field to be

555 555-3335 112

the node saves and is displayed just how I want it (with the parenthesis and x before the extension). But when I go to edit the node again the value of the field is back to (555) 555-3335 x112 and I get the validation error again when trying to save.

Ideally the validation would accept the parenthesis and x for the extension since it's confusing to some users to not be able to use common phone number markup. But at least the original value that the user provided should be saved to the database and used when editing the form.

My issue is different than #342748: Field length since that is an interface issue and mine appears to be a validation issue.