California Code, Penal Code - PEN § 27555

(a)(1) Commencing July 1, 2008, a person who is licensed pursuant to Chapter 44 (commencing with Section 921) of Title 18 of the United States Code may not sell, deliver, or transfer a firearm to a person in California who is licensed pursuant to Chapter 44 (commencing with Section 921) of Title 18 of the United States Code unless, prior to delivery, the person intending to sell, deliver, or transfer the firearm obtains a verification number via the Internet for the intended sale, delivery, or transfer, from the Department of Justice.

(2) If Internet service is unavailable to either the department or the licensee due to a technical or other malfunction, or a federal firearms licensee who is located outside of California does not possess a computer or have Internet access, alternate means of communication, including facsimile or telephone, shall be made available for a licensee to obtain a verification number in order to comply with this section.

(c)(1) If the department finds after the reviews specified in subdivision (b) that the intended recipient is authorized to receive the firearm shipment, the department shall issue to the inquiring party, a unique verification number for the intended sale, delivery, or transfer.  One verification number shall be issued for each sale, delivery, or transfer, which may involve multiple firearms.

(2) In addition to the unique verification number, the department may provide to the inquiring party information necessary for determining the eligibility of the intended recipient to receive the firearm.

(3) The person intending to sell, deliver, or transfer the firearm shall provide the unique verification number to the recipient along with the firearm upon delivery, in a manner to be determined by the department.