See 47 U.S.C. § 227(b). Nevertheless, the weight of authority suggests that consent may be revoked under the TCPA and that if messages continue after consent is revoked, those messages violate the TCPA. See, e.g., Gager v. Dell Fin. Servs., LLC, 727 F.3d 265, 268-272 (3d Cir. 2013); Beal v. Wyndham Vacation Resorts, Inc., --- F. Supp. ----, 2013 WL 3870282, at *16 (W.D. Wis. June 20, 2013); Adamcik v. Credit Control Servs., Inc., 832 F. Supp. 2d 744, 749 (W.D. Tex. 2011); Moore v. Firstsource Advantage, LLC, No. 07-CV-770, 2011 WL 4345703, at *11-12 (W.D.N.Y. Sept. 15, 2011); Brook v. Suncoast Schs., FCU, No. 8:12-cv-01428-T-33MAP, 2012 WL 6059199, at *4 (M.D. Fla. Dec. 6, 2012); Sengenberger v. Credit Control Servs., Inc., No. 09 C 2796, 2010 WL 1791270, at *4 (N.D. Ill. May 5, 2010). Although the Ninth Circuit has not addressed this question, at least one district court in the Ninth Circuit has. Gutierrez v. Barclays Grp., No. 10cv1012 (BGS), 2011 WL 579238, at *4 (S.D. Cal. Feb 9, 2011)

Other courts have concluded that consent can be revoked, but only through writing. E.g., Starkey v. Firstsource Advantage, LLC, 2010 WL 2541756, *5–6 (W.D.N.Y. Mar. 11, 2010); Cunningham v. Credit Management, L.P., 2010 WL 3791104, *5 (N.D.Tex. Aug. 30, 2010); Moore v. Firstsource Advantage, LLC, 2011 WL 4345703, *11 (W.D.N.Y. Sept. 15, 2011); Moltz v. Firstsource Advantage, LLC, 2011 WL 3360010, *6 (W.D.N.Y. Aug. 3, 2011); Sengenberger v. Credit Control Services, Inc., 2010 WL 1791270, *4 (N.D.Ill. May 5, 2010). In those cases, the courts relied on the fact that the cases involved debt collection calls and that the Fair Debt Collection Practices Act generally applies to debt collection.