Use your computer as a Bluetooth speakerphone(techsansar.com)

    * Click Start -> Control Panel -> Hardware and Sound -> Bluetooth Devices. (In Windows Vista OS, you might be prompted for Administrative credentials.)
    * On the Devices tab, click Add to add your mobile phone and then follow the wizard steps.
    * On your Mobile phone, enable Hands-free connection with your computer with enabling Bluetooth ON. (For details on using Bluetooth on your mobile phone, please read the documentation of your cell phone.)
    * Now, click Audio tab where you see your mobile phone in the list.
    * Click Telephony Audio Gateway service and then click Connect. When you are finished with the call, click Disconnect.