After the FX-5500 batteries have been charged for 6 hours, unplug the power adapter of the set to be registered from the wall socket. 

Then follow the "register extra handset" instructions in the user manual to register the extra handset to the main set.

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 serve you in the best possible way.