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Advanced Service Interworking
When the Q.931 QSIG protocol profile is selected, the QSIG facility element encoding defaults to ETSI
1995.
To change the facility coding definition manually, you must make changes in two windows as follows:
Go to Configuration / Q.931 Services.
Step 1
Set Facility Element Coding Standard to ISO (ISO 1994), ETSI (ETSI = ETSI 1995), or ECMA
Step 2
(ECMA = ETSI 1993), and click SUBMIT.
Step 3
Go to Configuration / Inter-Working.
Set Facility Element coding to ISO if you need either the ISO 1994 or the ETSI 1995 definition, or
Step 4
ETSI for the ECMA 1993 definition, and click SUBMIT.
Note
Cisco Systems, Inc., suggests that you contact your Q.931 equipment supplier if one or more
Supplementary services will not interoperate with its default ETSI (1995) encoding and you suspect the
Q.931 equipment may be operating to an alternative standard. With some PBX equipment, more service
capabilities are available with the PBX configured for ECMA (1993) rather than ISO operation.
QSIG Diversion Restriction
Certain DPNSS PBXs enforce an arbitrary constraint that prohibits a network user from diverting the
phone to an off-net number (for example, a national mobile number). In a mixed network that includes
such PBXs, the feature permits those QSIG PBXs that are capable of performing "call forward by join"
to offer off-net diversion without the diversion request being referred back to and rejected by the DPNSS
PBX.
In DPNSS, on determining that a call is being attempted to a phone against which a diversion is
registered, the destination PBX signals this to the originating PBX. It should then attempt a new call to
the "divert to" number that is 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.
This can be controlled by setting Reject Diversion Request for Numbers Longer than.
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. Cisco VG30D Voice
Gateway can now get 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, Cisco VG30D Voice Gateway units allow the QSIG diversion request to "interwork"
with the DPNSS PBX as normal. After it is configured, the diversion interception action acts entirely
automatically, and you can only turn it off by reconfiguring the option.
Using Diversion Restriction
The diversion restriction problem has been encountered specifically in networks that contain Ericsson
MD110 PBXs that are using DPNSS signalling.
Cisco VG30D Voice Gateway User Guide
6-8
Beware the discrepancy between meanings of the ETSI selection in the two different windows.
Chapter 6
Conversions and Transparency
OL-19276-01
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