Your A55 Cordless phone has a charging base which has a very safe low-voltage charging system. It will recharge the batteries with a “trickle charge”. This type of charge is very good for the phone’s batteries because it protects the condition of the batteries by not putting higher levels of voltage through it so quickly. The red light in the base will flash while this "trickle charge" is taking place.
Each time the handset is removed from the base and then replaced, the charging system will repeat it’s battery conditioning cycle to condition the battery to work at maximum efficiency.