SERVICE CONTINUITY AFTER AN APPLICATION SERVER FALLBACK

摘要

The present invention faces the issue of reselecting a preferred Service Call Continuity Application Server (SCC-AS) once this preferred SCC-AS is reachable again after a failure. To solve this issue, the present invention provides for an Access Transfer Control Function (ATCF) node receiving and storing an SCC-AS identifier, which identifies a selected SCC-AS, which is not the preferred SCC-AS, and transmitting a further received initial call setup message, toward the selected SCC-AS via a Serving Call Session Control Function (S-CSCF) along with the stored SCC-AS identifier. The S- CSCF finds the preferred SCC-AS is reachable again and transmits the received initial call setup message with the received SCC-AS identifier toward the preferred SCC-AS. The preferred SCC-AS determines a mismatch between the received SCC-AS identifier and its own SCC-AS identifier, and updates the ATCF node via the S-CSCF node with its own SCC-AS identifier that identifies the preferred SCC-AS.