- Call blocking technology - 10 polyphonic ringer melodies - Hands-free speakerphone - 50 name and number phonebook - Digital answering machine option The Motorola CD4 is perfect for everyday calling. An easy to use, newly designed phone, it comes with a host of features including a 10 number nuisance call blacklist with a dedicated key for direct access to the Call Block menu. It also features a loud speaker to free up your hands when needed and a 50 name and number phonebook.