Device and method for performing an internet protocol multimedia subsystem service

A communication device for performing an Internet Protocol (IP) Multimedia Subsystem (IMS) service with a network, comprising:

• a storage device;
• and
• a processing circuit, coupled to the storage device, wherein the storage device stores, and the processing circuit is configured to execute instructions of:
• transmitting a Protocol Data Unit (PDU) Session Establishment Request message requesting to establish a PDU Session for the IMS service, to the network;
• receiving a PDU Session Establishment Accept message configuring the PDU Session from the network, in response to the PDU Session Establishment Request message;
• configuring a plurality of data radio bearers (DRBs) associated to the PDU Session for the IMS service according to at least one configuration received from the network;
• communicating a plurality of IMS signaling messages for the IMS service on a first DRB of the plurality of DRBs with the network;
• and
• communicating a plurality of IMS data packets for the IMS service on a second DRB of the plurality of DRBs with the network.

A first communication device for performing an Internet Protocol (IP) Multimedia Subsystem (IMS) service with a second communication device, comprising:

• a storage device;
• and
• a processing circuit, coupled to the storage device, wherein the storage device stores, and the processing circuit is configured to execute instructions of:
• performing a first Protocol Data Unit (PDU) Session Establishment procedure to establish a first PDU Session for transmitting a plurality of IMS signaling messages for the IMS service with the second communication device;
• performing a second PDU Session Establishment procedure to establish a second PDU Session for transmitting a plurality of IMS data packets for the IMS service with the second communication device;
• configuring a first data radio bearer (DRB) associated to the first PDU Session to communicate with the second communication device;
• communicating the plurality of IMS signaling messages for the IMS service on the first DRB with the second communication device;
• configuring a second DRB associated to the second PDU Session to communicate with the second communication device;
• and
• communicating the plurality of IMS data packets for the IMS service on the second DRB with the second communication device.