MyMSUHealth portal users: Patients with a MyMSUHealth ... MSU Health Care Patient Accounts PO Box 18455 Belfast, ME 04915-4079. By Phone. Payments are accepted by phone. Call 1-800-964-3968 Monday through Friday from 8 a.m. - 5 p.m. It is best if you have your invoice or statement with you, but if you don't, we can look up your information ....