title This is a title participant UserA participant A participant B participant UserB UserA->A: REQUEST UserA->A: SETUP UserA<-A: CALL PROCEEDING #A->B: ISUP IAM UserA<-A: FACILITY UserA<-A: PROGRESS UserB<-B: SETUP UserB->B: CALL CONFIRM UserB->B: ALERTING # B->A:ISUP IAC UserA<-A: ALERTING UserB->B: CONNECT #B->A: ISUP ANSWER A->UserA: CONNECT UserA->A: CONNECT ACK B->UserB: CONNECT ACK UserA->A: DISCONNECT #A->B: ISUP Release A->UserA: Release UserA->A: Release complete B->UserB: Disconnect UserB->B: Release #B->A: ISUP Release Complete B->UserB: Release Complete