A number forwarding / CLIP no screening
Call forwarding (or call diverting), is a feature that allows an incoming call to a called party, which would be otherwise unavailable, to be redirected to a mobile telephone or other telephone number where the desired called party is situated.
Normally the system sends the CLIP information from the called party to the phone where the call is redirected to.
When using A number forwarding, the system sends the CLIP information from the incoming call to the phone where the call is redirected to. The called party will directly see who is calling and can respond accordingly.
To enable A number forwarding in your Gigaset T300/500 PBX system, you need to activate the No Screening feature in the extended line settings.
No Screening: The feature CLIP No Screening enables an alternative number to be sent and displayed to the call recipient on outgoing calls. availability of these features is service provider dependent.
Phone Number Prefix: If No Screening is activated, the Gigaset T500/300 PRO PABX may have to be changed to match the service provider's specification regarding the phone number format of the dialling code.
Please clarify this with your provider.