The Telephone Consumer Protection Act (TCPA) itself does not specifically define “prior express consent” in the statute, but an agreement, written or oral, clearly indicating consent to receive calls at a particular number constitutes prior express consent. For non-marketing calls, if a consumer knowingly provides a phone number to a company in the normal course of business, without conditions, express consent can be implied so long as the messages closely relate to the purpose for which the number was originally provided.

This same standard is also applicable to faxes. In Physicians Healthsource, Inc. v. Cephalon, Inc., et al., the Third Circuit found that providing a business card that included a fax number constituted "prior express consent" to receive faxes.