The Provider Service Center helps with contracting, patient services, precertification and many other questions. HMO and Medicare Advantage - 1-800-624-0756 (TTY: 711) Indemnity and PPO-based plans - 1-888-MD AETNA (1-888-632-3862) (TTY: 711) Voluntary plans - 1-888-772-9682 (TTY: 711) Worker's comp - 1-800-238-6288 (TTY: 711) ASA and Meritain - use phone number on member's ID card.