Bill Pay For visits starting December 6, 2018Pay Online: The convenient and efficient way to pay your bill is to log on to Mass General Brigham Patient Gateway. You can see the current status of all open patient balance and payments are immediately posted to your account.Call: (617) 726-3884 (8:00 a.m. - 4:30 p.m. EST)Mail: Send a check or money order to Mass General Brigham System:Mass ....