Federal Deception Law: 6.3.6.5.1 Consumers have the right to revoke consent at any time, in any reasonable way
Consent may be revoked at any time, in any reasonable way. In 2015, the FCC issued a declaratory ruling that reiterated this specifically:
[C]onsumers may revoke consent in any manner that clearly expresses a desire not to receive further messages, and . . . callers may not infringe on that ability by designating an exclusive means to revoke. . . .