Cisco Cisco Unified Contact Center Enterprise 9.0(2) Design Guide

"In-flight" calls are those that have been received by the Unified Expert Advisor runtime server but have 
not yet been connected to an expert advisor.

Expert advisors log their presence clients into Cisco Unified Presence, not to Unified Expert Advisor, so 
the presence clients are not affected by a failover. They will, however, receive a Message Set message 
indicating that there was a technical problem and warning them about conducting call control operations. 
The standby runtime server automatically takes over the job of managing each advisor's agent state with 
respect to Unified ICM; however, it does not know which advisors are already talking to callers. 
Therefore it is possible that some advisors are assumed to be ready and available, and could receive 
pop-up task offers when they are already on a call, just as they might when talking on the phone for any 
reason unrelated to Expert Advisor activity. Advisors are of course free to ignore or decline such offers.

The reporting server is always simplexed and always listening to reporting events from both runtime 
servers. There is little likelihood that conflicting events will be received because, at any given time, one 
call is under the control of one runtime server. If conflicting events ever do occur, database triggers 
automatically prevent them from entering the database.

If the reporting server fails or goes out of service for any reason, reporting events are automatically 
buffered within the runtime server. The size of this buffer space is configurable, and currently the default 
of 2 Gbytes is the recommended size. This is enough to support several days of normal operation. If it 
runs out, however, calls continue to be processed normally but newly arriving reporting events will be 
lost.

Expert advisor state change events with respect to various assignment queues are continually received 
by the reporting server. These events are not affected by a runtime server failover; the reporting server 
will simply continue receiving them from the backup runtime server.

All new calls are routed to the standby server.

All new calls are routed to the standby server.

All existing, connected calls remain fully 
operational until completed.

All existing, connected calls remain connected 
until completed, but call control operations such 
as transfer and hold can cause the call to drop, in 
which case Unified CVP would issue a 
Unified ICM re-query.

"In-flight" calls continue normally on the formerly 
active server as long as there is a possibility that 
any advisor has been offered the task. If not, they 
are rejected and Unified CVP issues a 
Unified ICM re-query. If Unified CVP is not part 
of the deployment, then a SIP error code is 
returned to the SIP user agent that sourced the call.

"In-flight" calls time-out at Unified CVP, and a 
Unified ICM re-query is invoked. If Unified CVP 
is not part of the deployment, then it is up to the 
SIP user agent that sourced the call to implement 
its own time-out mechanism.