For more information about enrolling in Medicare, look in your copy of the “Medicare & You” handbook, call Social Security at 1-800-772-1213, or visit your local Social Security office. If you get benefits from the Railroad Retirement Board (RRB), call your local RRB office or 1-800-808-0772.
https://www.hhs.gov/answers/medicare-and-medicaid/what-is-medicare-part-b/index.html

