Apple Inc.
Call Setup Time in Loaded IMS Networks

Abstract:

A device, system, and method improve a call setup time. The method is performed at a device configured to establish first and second network connections where the second network performs circuit switched voice calls. The method includes receiving a call input to perform a call and determining whether the device is registered with a first feature to perform the call based on an Internet Protocol (IP). When the device is registered with the first feature, the method includes determining whether timeouts for attempting previous IP calls is greater than a threshold. When the timeouts are at least the threshold, the method includes deregistering from the first feature and performing a circuit switched fallback (CSFB) procedure including a handover from the first network to the second network. The method includes performing the call as a circuit switched call.