At least once a month, do the following:
The Phone Body
Moisten a cloth with the dishwashing liquid solution and wipe the surface of the telephone. For hard-to-reach spots, such as the spaces between raised numbers, use cotton swabs dipped in rubbing alcohol. Be careful not to get any liquid near the hook-switch, speaker, or other openings.
Clean the handset with a cloth soaked with rubbing alcohol; since this is the part of the phone that touches your face, it is important to disinfect it. Be very careful not to pour alcohol directly onto the phone. You can also use premoistened disinfectant wipes to clean the handset.
To clean a dirty cord, remove it from the phone, and dampen a cloth with water and a few drops of mild dishwashing liquid. Rub the cord down with the cloth, and dry with a second cloth. Make sure the cord is absolutely dry before you reattach it to the phone.