McDewey

TAPI messages CTI messages Action A: LINE_APPNEWCALL, LINE_CALLSTATE (LINECALLSTATE_DIALTONE/ LINECALLSTATE_DIALING) CallerID = A / CalledID = “” A receives NewCallEvent and CallStateChangeEvent (Dialtone/Dialing) A dials 1000, this call first will be intercepted by CCD Requesting Feature, and CCD Requesting feature will extend this call to SIP trunk LineA: LINE_CALLSTATE (LINECALLSTATE_PROCEEDING)/ LINE_CALLINFO CallReason = LINECALLREASON_DIRECT CallerID = A / CalledID = 1000 / ConnectedID = / RedirectingID = / RedirectionID = A receives CallStateChangeEvent (PROCEEDING) SIP trunk rejects this call due to no more bandwidth available CCD Requesting feature will start PSTN failover by directing this caller to 1000’s PSTN failover number, that is, 14089721000. Call is sent out to a PSTN GW Cisco Unified TAPI Developers Guide for Cisco Unified Communications Manager, Release 15 and SUs 482 Message Sequence Charts Message Sequence Charts