The FX-500 keeps its memory by the power which is supplied through the phone line. 

If the phone cable is disconnected for more than a few seconds, or in case of a digital line there is a modem failure of more than a few seconds, the memory may be lost and the programmed numbers will be gone. 

These numbers must then be reprogrammed.

If you have any further questions or comments, please contact us via this website.

Please fill in your question or complaint as clearly as possible, so that we can provide you with the best possible service.