On the Philips LFH-9850, the Voice Prompts guide users through the operation of the Philips Digital Telephone Desktop.  In case you have lost your voice prompt files – e.g. though formatting your memory card, you can download them for re-installation.
The link below will allow you to download the voice prompts aka wave prompts.
Copy this .dpm firmware file to the root of the memory card placed in the 9850.  When the file has been fully copied to the device, disconnect the USB connection to the PC and the upgrade will start automatically.
Note: Users with Windows 2000: Due to the nature of MS Windows 2000, the actual file transfer to the memory card might take up to 40 seconds. To view the DTD 9850 current firmware version just unplug the main power, waits a few seconds and okug it back in.  The device display will also indicate the firmware version number.

Verification Source: Philips Website