| CPC H04W 8/04 (2013.01) [H04W 12/03 (2021.01); H04W 12/06 (2013.01); H04W 80/08 (2013.01)] | 12 Claims |
|
1. A method implemented by an interrogating call session control function (I-CSCF), comprising:
pre-registering, via a first serving call session control function (S-CSCF), the a user equipment (UE) in a network, including:
receiving, via the network, a first request to access a service from the UE, the first request including an Internet Protocol (IP) address of a proxy call session control function (P-CSCF) associated with the UE;
generating a first message according to the first request to register the UE in the network;
transmitting, to the first S-CSCF, the first message, causing the first S-CSCF to perform actions including:
obtaining, from a home subscriber database (HSS), an authentication to provide the service; and
saving, to the HSS, the IP address of the P-CSCF;
receiving, from the first S-CSCF, a response to the first message confirming the registration of the UE;
receiving, via a network, a second request to establish a call session with the UE;
obtaining, from the HSS, the IP address of the P-CSCF of the UE;
sending, to a second S-CSCF, a first invite associated with the second request;
determining that no response is received from the second S-CSCF after a pre-set time period;
sending, to a third S-CSCF, a second invite associated with the second request, the second invite including the IP address of the P-CSCF of the UE and causing the third S-CSCF to perform actions including:
obtaining an authentication to establish the call session; and
sending, to the P-CSCF associated with the UE, a third invite associated with the second request; and
receiving, via the network, a confirmation that the call session with the UE is established.
|