Can a car dealership take a credit application with personal information over the phone?

They can absolutely do this; there is no law restricting how this information can be requested or provided. Phone, in fact, is generally more secure than the internet or email, since a call is point to point and can't be "hacked" without wiretapping, which is VERY rare (other than when the police are monitoring someone). As long as you are confident about the person or business you are contaciting and that you have the right information, this should be as secure as doing it in person. Of course, if you have any qualms or doubts about the business or the specific person you're dealing with, you should not provide this information--but then again, you should not provide it in person to them in that case, either.