Methods, systems, and computer readable media for exchanging outbound registration count information among interrogating call session control functions (i-CSCFs) and using the outbound registration count information for serving cscf (s-cscf) selection

A system for exchanging outbound registration count information among interrogating call session control functions (I-CSCFs) and using the outbound registration count information for serving CSCF (S-CSCF) selection, the system comprising:

• a first I-CSCF of a plurality of I-CSCFs in a cluster of I-CSCFs, the first I-CSCF including at least one processor and a memory;
• an updated registration capacity calculation module executable by the at least one processor for receiving, from each of a plurality of S-CSCFs in a cluster of S-CSCFs, a value indicating a registration capacity of the S-CSCF, receiving, from at least one other I-CSCF in the cluster of I-CSCFs, outbound registration counts indicating numbers of outbound registrations that the at least one other I-CSCF has with the S-CSCFs in the cluster of S-CSCFs, and calculating, using the values indicating the registration capacities of the S-CSCFs and the outbound registration counts, values indicating updated registration capacities of the S-CSCFs, wherein the updated registration capacity calculation module is configured to receive the outbound registration counts via a Diameter interface, wherein the updated registration capacity calculation module is configured to receive the outbound registration counts via Diameter service association request (SVR) messages, wherein the Diameter SVR messages each include an outbound registration count attribute value pair (AVP) that carries the outbound registration counts, and wherein the outbound registration count AVP includes an S-CSCF name and a corresponding outbound registration count;
• and
• an S-CSCF selection module executable by the at least one processor for using the values indicating the updated registration capacities to select an S-CSCF for at least one outbound registration message.

A non-transitory computer readable medium having stored thereon executable instructions that when executed by a processor of a computer control the computer to perform steps comprising:

• receiving, at a first interrogating call session control function (I-CSCF) of a plurality of I-CSCFs in a cluster of I-CSCFs and from each of a plurality of serving CSCFs (S-CSCFs) in a cluster of S-CSCFs, a value indicating a registration capacity of the S-CSCF;
• receiving, at the first I-CSCF and from at least one other I-CSCF in the cluster of I-CSCFs, outbound registration counts indicating numbers of outbound registrations that the at least one other I-CSCF has with the S-CSCFs in the cluster of S-CSCFs, wherein receiving the outbound registration counts includes receiving the outbound registration counts via a Diameter interface, wherein receiving the outbound registration counts via the Diameter interface includes receiving the outbound registration counts via Diameter service association request (SVR) messages, wherein receiving the outbound registration counts via the Diameter SVR messages includes receiving the outbound registration counts via an outbound registration count attribute value pair (AVP) included in each of the Diameter SVR messages, and wherein receiving the outbound registration counts via the outbound registration count AVP includes receiving, for each of the S-CSCFs with which the at least one other I-CSCF has active registrations, an S-CSCF name and a corresponding outbound registration count;
• calculating, by the first I-CSCF and using the values indicating the registration capacities of the S-CSCFs and the outbound registration counts, values indicating updated registration capacities of the S-CSCFs;
• and
• using, by the first I-CSCF, the values indicating the updated registration capacities to select an S-CSCF for at least one outbound registration message.