Okla. Stat. tit. 5A , app 1-A § 9.1
When the action of the Supreme Court becomes final, a lawyer who is disbarred or suspended, or who has resigned membership pending disciplinary proceedings, must notify all of the lawyer's clients having legal business then pending within twenty (20) days, by certified mail, of the lawyer's inability to represent them and the necessity for promptly retaining new counsel. If such lawyer is a member of, or associated with, a law firm or professional corporation, such notice shall be given to all clients of the firm or professional corporation, which have legal business then pending with respect to which the disbarred, suspended or resigned lawyer had substantial responsibility. The lawyer shall also file a formal withdrawal as counsel in all cases pending in any tribunal. The lawyer must file, within twenty (20) days, an affidavit with the Commission and with the Clerk of the Supreme Court stating that the lawyer has complied with the provisions of this Rule, together with a list of the clients so notified and a list of all other State and Federal courts and administrative agencies before which the lawyer is admitted to practice. Proof of substantial compliance by the lawyer with this Rule 9.1 shall be a condition precedent to any petition for reinstatement.
Okla. Stat. tit. 5A , app 1-A § 9.1