Indicating a user equipment that it must register

The invention claims an introducing network, the network providing service to the register user, wherein the method comprises the steps: Recess (A1) service quest from user network device (UE), the inspection card is logging on user is further non-registration the user, and; and user is a non-registration user, generating and transmitting (A2 B3, comprising an alarm information of acknowledge message to B4) of acknowledge message to client network device (UE). The invention further claims a corresponding network device. , Wherein the user capable of network any acquiring service, informing a user flowing register.