Call 866-606-3700 for more information. Call Member Services at 866-606-3700 (TTY: 711) Monday - Friday, 7 a.m. to 5:30 p.m. memberservices.il@mhplan.com. Meridian Health Plan of Illinois, Inc. is rated 3.5 out of 5 in NCQA's Medicaid Health Insurance Plan Ratings 2016-2017 and NCQA's Medicaid Health Insurance Plan Ratings 2017-2018.Join Our Plan‧Benefits & Coverage‧Pharmacy‧News‧Health Library‧COVID-19.