This behavior is new feature of ASAI link version 7.
When called side is already talking and does not have enough call appearance for getting further call, further call fails as "busy".
FailedEvent is sent for informing call failed by busy.
At the environment of CM6.3.3(FP4) or later and AES6.3.3 or later, ASAI link version 7 provides this feature as one of "CTI events for undelivered calls". Please refer to following articles.
Avaya Aura® Application Enablement Services R6.3.3 Server and Client Release Notes
http://support.avaya.com/css/P8/documents/100180542
WHAT’S NEW IN AE SERVICES 6.3.3?
CTI events for undelivered calls
Avaya Aura® Application Enablement Services TSAPI for Avaya Communication Manager Programmer’s Reference Release 6.3.3
https://downloads.avaya.com/css/P8/documents/100180943
What’s New for the AE Services Release 6.3.3 TSAPI Service
Undelivered Call Events
Beginning with AE Services Release 6.3.3, Avaya Communication Manager Release 6.3.6, and ASAI Link Version 7, the TSAPI Service provides CSTA Unsolicited events to indicate that a call could not be delivered to a monitored station. For example:
If a call cannot be completed because the called station does not have a call appearance available to receive the call or because the Limit Number of Concurrent Calls feature is active, a device monitor for the called station receives a CSTA Failed Event.
