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UM380 03 010
InterChange iQ 2000 and iQ 2000plus
In DPNSS, on determining that a call is being attempted to a ‘phone against which a
diversion is registered, the destination PBX signals this back to the originating PBX. It
should then attempt a new call to the ‘divert to’ number identified by the destination PBX.
Certain DPNSS PBXs enforce an arbitrary limit on the length of the ‘divert to’ number. If it
exceeds that length, the PBX will not attempt to divert the call and the call fails.
Some QSIG PBXs overcome this restriction, without requiring action from the originating
DPNSS PBX, by making the diverting leg of the call and joining the new and original call
legs. InterChange iQ 2000 can now be set up to detect the condition (overlong divert-to-
number) and change its signalling to trigger the QSIG PBX to take alternative diversion
action. Where the length of the divert to number is not excessive, InterChange iQ 2000 units
allow the QSIG diversion request to ‘interwork’ with the DPNSS PBX as normal.
Once configured, the diversion interception action is entirely automatic. It can only be turned
off by reconfiguring the option.
Using Diversion Restriction
The diversion restriction problem has been encountered specifically in networks containing
Ericsson MD110 PBXs using DPNSS signalling.
Limitations to Diversion Restriction
Diversion Restriction should not be used unless:
•
the originating PBX refuses to implement certain kinds of diversion.
•
you are certain your QSIG PBX(s) can perform call forward by join.
Note:
Call forward by join can result in non-optimal bearer paths (trombones). Because of the
particular way the path is created, these may not always be optimised by subsequent path
replacement requests.
Configuring Diversion Restriction
Changes in diversion behaviour can only be made using the InterChange iQ 2000 installation
menus. The option is offered in the Q.931
CUST
(customer specific configuration) menu.
Type
DISP
to display current settings and
CHNG
to change these settings. You will be
asked a series of detailed questions; press
Return
to proceed to the next question without
changing the current setting. The last question is:
Reject Rerouting requests to long numbers (yes/no) ?
Type
YES
and a supplementary question is asked:
Enter max. digits to allow in DVT request (0 to disable restriction) ?
Type in the length of the longest number you want to be referred back to the DPNSS PBX for
diversion action. Definity will be stimulated to attempt its own diversion on target numbers
exceeding this length. Type
0
to clear the restriction.
