Yes, it is possible to shift between a mobile phone and the BW900 base station in the following 2 ways when the system are in standby (no calls/audio):

1. You can seemlessly shift between the base and the mobile phone by press and hold the hook button of the headset for about 2 sec. This function will also try to activate your "voice-dail" if your mobile phone support this.
2. Double push the hook button on BW 900 headset and you will simply connect to the mobile phone.