You can connect the following to your Gigaset DE900 IP PRO:
A maximum of one device can be connected via Bluetooth and one device via DECT.
If I connect a DECT handset/headset and a mobile phone via Bluetooth, can I answer the incoming call via the mobile phone on the handset/headset?
No, the DECT and Bluetooth interface share one voice path. They can be activated simultaneously but cannot be used at the same time.