A communication device comprising a central processing unit (CPU) and a memory device is disclosed. The CPU is configured to send a first attach request including a first subscription identity (FSI) to the network apparatus, receive an authentication request including a random number and an authentication token from the network apparatus as a response to the first attach request. Further, the CPU is configured to authenticate the authentication token using the random number and a first key associated with the FSI, obtain a second key and a second subscription identity (SSI) in response to authentication of the authentication token failing, where SSI is obtained from the authentication request. The CPU is further configured to send an authentication failure to the network apparatus. The second key and SSI are stored in the memory device such that the second key is associated with SSI.