A party may compel discovery from a nonparty--that is, a person who is not a party or subject to a party's control--only by obtaining a court order under Rules 196.7, 202, or 204, or by serving a subpoena compelling:
A party seeking discovery by subpoena from a nonparty must serve, on the nonparty and all parties, a copy of the form of notice required under the rules governing the applicable form of discovery. A notice of oral or written deposition must be served before or at the same time that a subpoena compelling attendance or production under the notice is served. A notice to produce documents or tangible things under Rule 205.3 must be served at least 10 days before the subpoena compelling production is served.
Tex. R. Civ. P. 205