After about 15sec press the DECT button on the Fritz! Box 7390 the C4 was logged. The phonebook entries in the box appeared on the display of the C4, you're able. Charge lasts effortlessly for two days. The Spachqualität is particularly high among the phone users, the! Also a Fritz Fon. The other "gimmicks" are quite nice, but radio, e-mail and Podcast I use otherwise rather different. Especially useful I find that the ECO mode DECT radiation-free will (for the most sensitive contemporaries intended indispensable and it also protects the battery yet) ....