2.4 GHz Frequency Hopping Spread Spectrum (FHSS) Technology: FHSS technology provides clear sound over longer ranges, as well as digital security to prevent eavesdropping. Digital Speakerphone (Handset): You can answer the phone without interrupting what you are doing - whether you are cooking, cleaning, or surfing the Internet. Light-Up Indicator with Ringer Alert (Handset). The indicator on the handset lights up in amber when there is an incoming call for visual confirmation. Convenient AAA (R03) Ni-MH Rechargeable Battery (Handset). Since AAA-type rechargeable batteries are used, you can replace them with two commercially available AAA batteries for added convenience. (Rechargeable Battery: HHR-4MRT). Illuminated Display (Handset). Whenever you get a call or touch a key, the LCD&s backlight lights up, so even in the dark you&ll be able to see who&s calling and easily operate the phone. 50-Name & Number Phonebook. Up to 50 station names and numbers can be stored in the built-in phonebook for fast, easy recall. Caller ID with 50-Name & Number Call Log. The handset LCD displays the caller&s name and number, so you can see who&s calling before you actually answer the phone.