From Dear AFA:

Flight Attendants that have active Family Medical Leave (FML) approval usage on file the week of February 9, 2009 will receive a letter from United. The purpose of the letter is to advise Flight Attendants of a unique case number that will be assigned to each separate FML authorization. 

Using this case number will help maintain confidentiality, resulting in no longer needing to identify if the FML usage is for themselves or the care of a family member, and providing these specifics to the service center. The case number will also allow United to monitor frequency and duration and differentiate between the multiple reasons for FML requests. This process has been in use by all other employee groups since the centralization of the FML process.

When calling the Flight Attendant Service Center (FASC) to place yourself on FML sick leave status, you will be asked for your case number. If you do no thave the case number you may request to be transferred to the Employee Service Center (ESC) to obtain your case number, and then transferred back to the FASC. If the ESC is not open you will be placed ONSL, and it will be necessary to contact the ESC, obtain your case number and provide it to the FASC to be converted from ONSL to FML. 

The ESC may be contacted directly at 866-825-4104. The FASC does not have access to any confidential information, nor do they have access to pull up any FML information.