Cal. Pub. Util. Code § 2889.5
(a) No telephone corporation, or any person, firm, or corporation representing a telephone corporation, shall make any change or authorize a different telephone corporation to make any change in the provider of any telephone service for which competition has been authorized of a telephone subscriber until all of the following steps have been completed:
(3) For sales of residential service, the subscriber’s decision to change his or her telephone service provider shall be confirmed by an independent third-party verification company, or as provided in paragraph (5). For purposes of this provision, the confirmation by a third-party verification company shall be made as follows:
(A) The third-party verification company shall meet each of the following criteria:
(6) For sales of all nonresidential services, the subscriber’s decision to change his or her service provider shall be confirmed through any of the following means: