Patent ID: 11877224
Assignee: NOKIA TECHNOLOGIES OY
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An apparatus, comprising:
at least one processor; and
at least one memory including computer program code;
the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform:
transmitting a service request message;
starting a service request timer when the service request message is transmitted;
determining an expiration of the service request timer;
handling the expiration of the service request timer based on a service type of the service request message and based on a mobility management mode;
determining the service type of the service request message and for, when the service type of the service request message is the emergency service fallback type:
determining the apparatus is camping on a new radio cell connected to a 5G core network, an emergency service support indicator for access indicates that emergency services are supported in evolved universal terrestrial radio access connected to the 5G core network only, and the apparatus is capable of accessing the 5G core network via the evolved universal terrestrial radio access;
attempting to select an evolved universal terrestrial radio access cell connected to the 5G core network based on the determining; and
when the apparatus is unable to select an evolved universal terrestrial radio access cell connected to the 5G core network, attempting to select an evolved universal terrestrial radio access cell connected to an evolved packet core when the apparatus is configured to support S1 mode.