Call routing
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System functions and features as of R3.0
syd-0367/1.3 – R3.0 – 03.2013
6. 7. 1. 2
Clearing down Exchange-to-Exchange Connections
Digital-Digital (D-D):
The public network sends the communication server a release signal once the ex-
ternal call partners of an exchange-to-exchange connection have finished the call.
The connection can then be cleared down by the communication server.
Without a release signal, the communication server cannot clear down an ex-
change-to-exchange connection.
The amount of time between completion of the call and the sending of the release
signal depends on whether the exchange-to-exchange connection is set up end-
to-end within the ISDN network (end-to-end ISDN connection) or whether sections
of it are analogue (non-end-to-end ISDN connection).
At transitions to other networks (for example from leased-line-network to mobile
phone network) it is possible, due to the lack of correct signalling, that an end-to-
end ISDN connection is signalled as a non-end-to-end connection.
End-to-End ISDN Connection
The release signal is sent as soon as the call is completed.
Non-End-to-End ISDN Connection
With non-end-to-end ISDN connections the amount of time between the comple-
tion of the call and the release depends on who set up the connection:
• If the connection was set up by the internal user (i.e. from the communication
server’s viewpoint an outgoing call), and the external partner (user C in
)
hangs up, it can take a few minutes for the release signal to be sent.
• If the connection was set up by one of the external partners (i.e. from the com-
munication server’s viewpoint an incoming call) and the external partner (user B
in
) hangs up, the release signal is sent immediately.
Note:
If two announcement services such as sports and weather information
are connected with each other, this exchange-to-exchange connection
will not be cleared down automatically This can lead to high call charges.
Each exchange-to-exchange connection will be cleared down by the communica-
tion server after two hours.
