ACD contact center features
192 Communication Manager Guide to ACD Call Centers
Network Call Transfer
NCT occurs after the incoming call is initially answered. With NCT, the communication
server is required to set up the second leg of the call and then wait for the second site to
acknowledge before requesting the PSTN to transfer the first leg of the call to the second
leg, and before the PSTN drops the trunks to the communication server. The benefit is that
the communication server retains control over the call and can redirect the call using the
trunk-to-trunk method should the NCT invocation fail. Therefore, the NCT option is the
most reliable.
After the second leg of the call is initiated and acknowledged by the public switch, the
public network joins the original ISDN caller to the redirected-to endpoint and then drops
both the original ISDN call and the second leg of the call at the redirecting communication
server.
Network Call Deflection
NCD occurs before the incoming call is initially answered. With NCD, the public network
sets up the second leg of the call to the redirected-to location when the communication
server deflects the call. There are two PSTN options for NCD, per the ETSI standards:
“retain call until alerting/connect” and “clear call upon invocation.” This is commonly
referred to as a partial call reroute.
With the “clear call on invocation,” which is the only NCD operation currently available, the
communication server loses control of the call once the call has been transferred to the
public network for redirection. The communication server does not retain control of the call
until it has been acknowledged by the network, so there is no alternative transfer possible
if the public communication server cannot transfer the call to the second location.
The “retain call until alerting/connect” option is not widely available (no known PTSN offers
it at this time). With this option, the PSTN sets up the second leg of the call and waits until
an alerting message is received before the first leg of the call is dropped. In this case, if the
second leg of the call fails, then the communication server can redirect the call through
another method (such as trunk-to-trunk connection) and not lose the call.
