Since many doctors and hospitals participate in the Blue Cross and Blue Shield of Illinois PPO network, the directories are extremely large and costly. To contain costs and contribution rates, search the online list of Doctors & Hospitals. You can print a personal directory. You can also call the AT&T Customer Service Center at 1-800-621-7336 (Bargained), 1-855-439-3641 (Management) to determine if your doctor participates, or to find a participating doctor in your area. If you still want a printed directory, you may call the AT&T Customer Service Center.