PABX CCM Route Optimisation

Unanswered Question
Apr 6th, 2010


I have the following setup.

Siemens PABX - VG30D DPNSS/QSIG Converter - 2811 MGCP GWay - UCM V7.1.3 Cluster

The scenario is:

IPT Ext 8100 and 8101 are in a Call Pickup Group.

PABX Ext 2000 calls IPT Phone Ext 8000. Ext 8000 transfers call to an IPT Phone Ext 8100. Ext 8100 rings and the Ext 8101 uses Group Pickup to answer call.

The call is connected, however after 13 seconds Ext 8101 is disconnected. The originating PABX Ext 2000 now hears ring tone.

Debug ISDN Q931 on the Gateway confirms that a disconnect is received from the PABX.

PABX traces confirm that when the call is picked up by IPT Ext 8101 the PABX sends an optimisation message (110B), however this is being rejected by the Call Manager message (54).

Any suggestions would be appreciated.



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Aaron Harrison Tue, 04/06/2010 - 03:25


There are a few things to consider here...

As I recall, DPNSS pretty much has one way of requesting this feature.

CCM has some service parameters that control it the QSIG equivalent (under the CAllManager service parameters).

In your VG30D there will be settings to enable Route Optimisation on the DPNSS side, and path optimization on the QSIG side, and some other settings... so there are a few places where you might need to change settings.

So - are you sure that it's CallManager rejecting the connection? PBX-guy will say it is, but you have the VG30D in between which you also need to consider. Does that have the feature enabled on both trunks?

Have you checked the traces on the CallManager side?


iwearing Tue, 04/06/2010 - 07:02


Thanks for the feedback.

I have checked the VG30D and can confirm that Route Optimisation is enabled by default.


Aaron Harrison Tue, 04/06/2010 - 07:16


And on the Q.931 services side? Enabled there too?

Did you take a look at the logs on the CallManager?


iwearing Tue, 04/06/2010 - 07:26


Yes also enabled on the Q931 side.

Unfortunately I will have to schedule a site visit to gather traces.




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