You can select "E-mail US" online and ask for your Sabre PNR by giving them your original Shares PNR, flight number, FF number. I have never had a problem getting one by e-mail. Then you can look up your reservation online using the Sabre PNR under the tab, "My Trip."

If you do not have elite status on US, the only number I know to call is 800-428-4322 and you will probably get an overseas CS agent. If you have status, you should have an dedicated elite number.