IP Library Granted Patent US 12684022
Granted Patent B2
US 12684022 · App. 18/620,742 · Granted Jul 14, 2026

Techniques for improved service call session restoration

Inventors: Khurram Ahmad Mirza (Bellevue, WA); Madhuri Kotta (Bellevue, WA)
Assignee: T-Mobile USA, Inc.
H04L65/1045H04L65/1073H04L65/1016
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Quick Facts
Patent No.
US 12684022
App. No.
18/620,742
Granted
Jul 14, 2026
Kind
B2
Abstract

Techniques are described herein for providing improved service call session restoration. In embodiments, such techniques may comprise storing, at a home subscriber server (HSS), information about a proxy call session control function (P-CSCF) node. The HSS may then receive an indication that a first service call session control function (S-CSCF) node is unresponsive. Upon receiving such an indication, the techniques may comprise determining, based on a user profile, that the first S-CSCF node is associated with the P-CSCF node; selecting, based on the information about the P-CSCF node, a second S-CSCF node to be associated with the P-CSCF node; and providing, by the HSS, at least a portion of the information about the P-CSCF node to the second S-CSCF node. The second S-CSCF node can then be configured to replace the first P-CSCF node using that information.

Claims (36)

1 . A method comprising:

storing, at a home subscriber server (HSS), information about a proxy call session control function (P-CSCF) node in association with information about a specific user equipment (UE) that has a connection supported by the P-CSCF node;

receiving, at the HSS, an indication that a first service call session control function (S-CSCF) node is unresponsive, wherein the first S-CSCF node was also associated with the connection of the specific UE;

selecting, by the HSS and based on the information about one or more capabilities, a second S-CSCF node to replace the first S-CSCF node for the connection of the specific UE, wherein the second S-CSCF node is selected from a set of available S-CSCF nodes and the set of available S-CSCF nodes are identified via a domain name system (DNS) query;

receiving, by the HSS from the second S-CSCF node, a request for the information about the P-CSCF node; and

providing, by the HSS, at least a portion of the information about the P-CSCF node to the second S-CSCF node.

2 . The method of claim 1 , wherein the indication that the first S-CSCF node is unresponsive is received in relation to a communication directed toward the specific UE.

3 . The method of claim 2 , wherein the first S-CSCF node is associated with the P-CSCF node during a registration of the specific UE.

4 . The method of claim 1 , wherein the second S-CSCF node is selected using one or more vector similarity analysis techniques.

5 . The method of claim 4 , wherein the method further comprises generating a vector in which each of a number of capabilities supported by the second S-CSCF node are represented as a value along an axis in a multi-dimensional space.

6 . The method of claim 1 , wherein the indication that the first S-CSCF node is unresponsive comprises one of a lack of response from the first S-CSCF node or an error code received from the first S-CSCF node.

7 . The method of claim 1 , wherein the information about the P-CSCF node comprises an indication of one or more capabilities associated with the P-CSCF node.

8 . A Home Subscriber Server (HSS) computing device comprising:

one or more processors; and

one or more non-transitory computer-readable media storing computer-executable instructions that, when executed by the one or more processors, cause computing device to perform operations comprising:

storing information about a proxy call session control function (P-CSCF) node in association with information about a specific user equipment (UE) that has a connection supported by the P-CSCF node;

receiving an indication that a first service call session control function (S-CSCF) node is unresponsive, wherein the first S-CSCF node was also associated with the connection of the specific UE;

selecting, based on the information about one or more capabilities, a second S-CSCF node to replace the first S-CSCF node for the connection of the specific UE, wherein the second S-CSCF node is selected from a set of S-CSCF nodes determined to be available and the set of S-CSCF nodes determined to be available is identified based on a current workload or bandwidth usage;

receiving, from the second S-CSCF node, a request for the information about the P-CSCF node; and

providing at least a portion of the information about the P-CSCF node to the second S-CSCF node.

9 . The computing device of claim 8 , wherein the information about the specific UE is created upon registration of the specific UE.

10 . The computing device of claim 8 , wherein the information about the P-CSCF node comprises an indication of one or more capabilities associated with the P-CSCF node.

11 . The computing device of claim 8 , wherein the second S-CSCF node is selected based on a degree of similarity between the one or more capabilities and a second set of capabilities of the second S-CSCF node.

12 . A system comprising:

at least one proxy call session control function (P-CSCF) node;

multiple service call session control function (S-CSCF) nodes; and

a home subscriber server (HSS) configured to:

store information about the P-CSCF node in association with information about a specific user equipment (UE) that has a connection supported by the P-CSCF node;

receive an indication that a first S-CSCF node of the multiple S-CSCF nodes is unresponsive, wherein the first S-CSCF node was also associated with the connection of the specific UE;

select, based on the information about one or more capabilities, a second S-CSCF node to replace the first S-CSCF node for the connection of the specific UE;

receiving, from the second S-CSCF node, a request for the information about the P-CSCF node; and

provide at least a portion of the information about the P-CSCF node to the second S-CSCF node.

13 . The system of claim 12 , wherein the second S-CSCF node is caused to be configured to replace the first S-CSCF node using the received portion of the information about the P-CSCF node.

14 . The system of claim 13 , wherein the second S-CSCF node is configured to replace the first S-CSCF node before communicating with the P-CSCF node.

15 . The system of claim 12 , wherein the information about the P-CSCF node is received at the HSS when the specific UE is registered with the HSS.

16 . The system of claim 12 , wherein the information about the P-CSCF node is received at the HSS on a periodic basis.