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ASAI and Call Control
Issue 7 May 1998
4-27
Call Classification for Phantom Calls
Phantom calls are not classified by the ECS; however, there are cases in which
unsuccessful Phantom Calls are cleared by the ECS. For instance, if a Phantom
Call is placed over ISDN trunks and the called destination is busy, the ECS tears
down the call, and sends a Third Party Call End message to the application. This
message includes a cause value indicating the reason why the call is cleared, in
this case the cause value is “User Busy” (CS0/17).
It is strongly recommended that if Phantom Calls are placed over trunks, that
these trunks provide answer supervision and that applications provide a timing
mechanism to clear unanswered calls upon timer expiry. Otherwise, these calls
will tie-up resources unnecessarily.
Phantom Call Originator
The originator of a Phantom Call can be either a station Administered Without
Hardware (AWOH) or a hunt group which contains AWOH stations as its
members. Only analog and DCP stations can be AWOH originators for Phantom
Calls.
A station AWOH is available if it has at least one available call appearance and no
other active calls present.
If the originator specified is a hunt group, then the DEFINITY ECS will hunt for the
next available AWOH member. To be chosen as the originator, a hunt group
member must not have any calls either active or on hold. (A hunt group may have
a mix of stations with or without hardware, but only a station without hardware is
eligible to originate Phantom Calls.) The chosen station, not the hunt group, will
be reported as the calling party in any events associated with the call.
Phantom Call Destination
!
WARNING:
Do not place Phantom Call over trunks which do not provide disconnect
supervision.These calls will be denied.
!
WARNING:
It is advisable to use only those trunks which provide answer supervision;
otherwise the DEFINITY ECS feature “Answer Supervision by Call
Classifier” should be used to ensure that if the call goes unanswered, the
application is informed and can take action to disconnect the call, if needed.
Since Phantom Calls can be directed anywhere, it is up to the customer to
configure the application and the DEFINITY ECS in such a way that any
vector commands executed for such calls make sense.