Which of the following actions would probably NOT violate federal consumer protection laws?

The action that probably would not violate federal consumer protection laws is the creditor's repeated phone calls to collect debt. Under the Fair Debt Collection Practices Act (FDCPA), creditors are allowed to contact debtors, but they must adhere to certain guidelines regarding harassment and the frequency of calls. If the calls do not constitute harassment and fall within these legal parameters, they are typically considered lawful.

The other actions listed are clear violations of consumer protection laws. Untruthful advertising deceives consumers and is prohibited under various laws, including the Federal Trade Commission Act. Denying rescind rights in door-to-door sales overlooks the consumer's right to cancel such transactions, which is protected under the Cooling-Off Rule. Lastly, fraudulent telephone solicitations are illegal under laws that aim to prevent deceptive marketing and scams. Each of these actions constitutes a direct breach of well-established consumer protections designed to promote honesty and fairness in commercial transactions.