California Code, Revenue and Taxation Code - RTC § 6066

(a) Every person desiring to engage in or conduct business as a seller within this state shall file with the board an application for a permit for each place of business. Every application for a permit shall be made upon a form prescribed by the board and shall set forth the name under which the applicant transacts or intends to transact business, the location of his place or places of business, and such other information as the board may require.An application for a permit shall be authenticated in a form or pursuant to methods as may be prescribed by the board.The application shall state that the applicant will actively engage in or conduct business as a seller of tangible personal property.

(b) An application filed pursuant to this section may be filed using electronic media as prescribed by the board.

(c) Electronic media includes, but is not limited to, computer modem, magnetic media, optical disk, facsimile machine, or telephone.