Patent ID: 8560890
Filing Date: 2013-10-15
Classification: H04L

Abstract:
1. A method of recovery to be applied in an IP Multimedia Subsystem “IMS” after having detected a restart condition of a Home Subscriber Server “HSS” holding subscriber data for subscribers of the IMS, and after having received a registration from a given subscriber or an invitation to communicate with a given subscriber from another subscriber, the method comprising the steps of: detecting a restart condition in a HSS holding subscriber data for subscribers of the IMS; marking in the HSS all registered subscribers as ‘suffering Restart’; receiving at an Interrogating Call Session Control Function server “I-CSCF” a registration from a given subscriber or an invitation to communicate with a given subscriber; the I-CSCF querying the HSS about a selectable Serving Call Session Control Function server “S-CSCF” for serving the given subscriber; determining that the given subscriber is marked in the HSS as ‘suffering Restart’; querying relevant entities of the IMS to find the S-CSCF currently serving the given subscriber; receiving a positive response from the S-CSCF currently serving the given subscriber; assigning said S-CSCF in the HSS for serving the given subscriber; clearing the mark ‘suffering Restart’ for the given subscriber in the HSS; and selecting said S-CSCF in the I-CSCF for serving the given subscriber.