Unlike the various Gigaset systems I’ve considered in the past, the C610A is not an IP-capable system. It sports just one old school analog line interface. Normally I wouldn’t even trouble myself to take such a phone out of the box.
The C610A itself is a pretty basic phone. The DECT base includes voicemail capability, with a small speaker on the base so that you can listen to voice messages at the base even if the handset is elsewhere. The VM system can also be used to record a call in progress.