Why is the amount of contacts different on mobile device and Gigaset handset?
Sevaral phone numbers can be stored in a Smartphone contact. If these contacts are transferred than different contacts will be created in a DECT handset. That is dependent of the Gigaset handset. An A-class handset will have one phone number per contact. C, CL, E, S, SL- class handsets have 3 phone numbers per contact (Home, Private, Mobile).
Furthermore mobile device contacts without a number are not presented in the APP and cannot be transferred to a Gigaset handset.
Details can be found here.