This service is for the situation that a subscriber is the called subscriber. This service provided the calling subscriber number to the called subscriber. When the system is performing CF service, this service will display the calling subscriber number of the forwarded call on the original called subscriber’s mobile phone, and both the calling subscriber number and original called subscriber number on the forwarding destination subscriber’s mobile phone. This service is authorized, activated or deactivated by the carriers on the network side, and cannot be operated by mobile phones.