Patent ID: 7936683

Claim:
A method of monitoring network performance, the method comprising: receiving a session initiation protocol (SIP) response message from a particular serving-call session control function (S-CSCF) system of a plurality of S-CSCF systems at a centralized error monitoring server of an Internet Protocol (IP) Multimedia Subsystem (IMS), wherein the SIP response message is sent to the centralized error monitoring server when the SIP response message includes at least one error code included in an initial filter criteria of a calling device associated with the SIP response message, the initial filter criteria accessed by the S-CSCF system; incrementing one or more counters related to the at least one error code; returning the SIP response message from the centralized error monitoring server to the particular S-CSCF system, wherein the particular S-CSCF system is configured to send the SIP response message received from the centralized error monitoring server to the calling device; and sending an alert message to a fault management system of the IMS from the centralized error monitoring server when a number of error codes counted by a particular counter exceeds a threshold for the particular counter.