According to the Siemens website, the C610H handset is compatible with the C620. See link: http://www.gigaset.com/ch_de/cms/home/kundenservice/privatkunden/kompatibilitaet/compat/list/CompatEntry/GIGASETC620.html

Yes, the phone number is displayed and if Voip is available, the name is also displayed.

The best thing to do in this regard is to contact our customer service directly at https://helpcenter.digitec.ch/hc/de/requests/new. Your request can then be examined individually.

No. Gigaset products with answering machines usually have an A in the product title. For example, the following product: Gigaset C620A

Excerpt from the operating instructions "You can register a maximum of six handsets on your base station. You must register the handset on both the base station and the handset."

Good evening Yes, you can block the numbers directly on the device. That's a great thing! I'm quite happy with the device. Greetings