Every year, Medicare plans change what they cost and cover. So what may have worked for you last year may not be the most cost-saving option this year. Open enrollment ends Dec. 31. To review your options or switch plans, call Medicare 24 hours a day at 1-800-MEDICARE (633-4227). TTY users should call 1-877-486-2048. Or visit www.medicare.gov. Information is also available via your State Health Insurance Assistance Program (call Medicare for more information).