Apparatuses and methods for coordinating communication operations associated with a plurality of subscriber identity cards in a mobile communication device with a single wireless transceiver

A mobile communication device, comprising:

• a wireless transceiver, configured to perform wireless transmission and reception to and from a first service network and a second service network;
• and
• a controller, configured to use a first subscriber identity card to establish one or more first radio bearers with the first service network via the wireless transceiver, wherein when the one or more first radio bearers are established between the mobile communication device and the first service network, the mobile communication device is allowed to transmit one or more data packets to the first service network,
• the controller being further configured to:
• use a second subscriber identity card to set up an Internet Protocol Security (IPsec) tunnel with an evolved Packet Data Gateway (ePDG) of the second service network via the first radio bearers, and
• use the second subscriber identity card to register an IP Multimedia Subsystem (IMS) service with the second service network via the IPsec tunnel.