APPARATUSES AND METHODS FOR REDUCING CIRCUIT SWITCH FALLBACK (CSFB) CALL SETUP TIME

摘要

A mobile communication device including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from a first network supporting only Packet-Switched (PS) services or a second network supporting Circuit-Switched (CS) services. The controller receives a rejection message of a Tracking Area Updating (TAU) procedure from the first network via the wireless transceiver when a Circuit Switch Fallback (CSFB)-related call originated from or terminated to the mobile communication device is pending, determines whether the rejection message includes a predetermined rejection cause, and in response to the rejection message including the predetermined rejection cause, selects the second network to make the CSFB-related call via the wireless transceiver without re-attaching to the first network.

主权项

1. A mobile communication device, comprising:
a wireless transceiver, configured to perform wireless transmission and reception to and from a first network supporting only Packet-Switched (PS) services or a second network supporting Circuit-Switched (CS) services; and a controller, configured to receive a rejection message of a Tracking Area Updating (TAU) procedure from the first network via the wireless transceiver when a Circuit Switch Fallback (CSFB)-related call originated from or terminated to the mobile communication device is pending, determine whether the rejection message comprises a predetermined rejection cause, and in response to the rejection message comprising the predetermined rejection cause, select the second network to make the CSFB-related call via the wireless transceiver without re-attaching to the first network.