Methods for call management with multiple subscriber identity cards and apparatuses using the same

A method for call management, performed by a processing unit of a UE (user equipment), wherein the UE is equipped with a first subscriber identity card and a second subscriber identity card, which share a radio resource, comprising:

• providing a first PS (packet-switched) service for the first subscriber identity card;
• handing over packet data transmission and reception to a second PS service with the second subscriber identity card from the first PS service after receiving a call request requesting a CS (circuit-switched) service with the second subscriber identity card,
• wherein the handing-over step further comprises:
• performing a NAT (network address transition) after receiving the call request wherein the NAT replaces a destination address of an incoming packet with a first address corresponding to the first SIM and replaces a source address of a outputting packet with a second address corresponding to the second SIM;
• and
• canceling the NAT after the second PS service is released, and maintaining the NAT when the first services is terminated.