CA Civ Proc Code Section 2020.010

(a)

Any of the following methods may be used to obtain discovery within the state from a person who is not a party to the action in which the discovery is sought:

(1)

An oral deposition under Chapter 9 (commencing with Section 2025.010).

(2)

A written deposition under Chapter 11 (commencing with Section 2028.010).

(3)

A deposition for production of business records and things under Article 4 (commencing with Section 2020.410) or Article 5 (commencing with Section 2020.510).

(b)

Except as provided in subdivision (a) of Section 2025.280, the process by which a nonparty is required to provide discovery is a deposition subpoena.