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Conversions and Transparency
5.2 Transparent Signalling
5.2.1 Overview
The InterChange iQ 2000 and iQ 2000plus platform software allows end to end transparent
signalling between DPNSS PBXs via an Intervening QSIG Network
DPNSS over QSIG Transparency allows call control and supplementary service signalling
to be carried from a DPNSS network via an intervening network providing QSIG signalling
interfaces to another DPNSS network. The intervening network and Interchange units
simulate a single transit mode in a DPNSS network.
For transparency over QSIG the DPNSS conversion uses the QSIG Generic Functional
Protocol (GFP) for the transport of DPNSS signalling. GFP provides a framework within
which communicating InterChange iQ 2000s can exchange manufacturer specific information
without causing problems in the intervening equipment. To support DPNSS services
involving virtual call signalling, the QSIG network must also support call-indpendent signalling
connections (sometimes called temporary signaling connections).
Figure 42: DPNSS over QSIG Transparency.
The figure above shows how, once the DPNSS call leaves the InterChange iQ 2000 unit, the
transit across the intervening network is handled entirely by that network. It is not necessary
for the DPNSS PBX to provide information about the call further than the InterChange.
The routing functions of the central network remain fully available, so transparent signalling
can be effected between any number of Interchange-connected attached PBXs.
When calls arrive at a non-Interchange-connected PBX then the normal DPNSS/ Q.931
conversion functionality of an InterChange iQ 2000 or iQ 2000plus applies, as described in
Section 5.1
, plus a limited number of further Supplementary Services.
5.2.2 Supported Services
InterChange iQ 2000 and iQ 2000plus provide transparency for:
•
Basic Call BTNR 188 [Ref. B.24] Sections 6 and 7.
•
Supplementary Services BTNR 188 [Ref. B.24] Sections 8 - 26, 28-48 with the
exception that options within some services which use Single Channel Working are
not supported.
•
BTNR 188 Section 27 applies to Traffic Channel maintenance services between
adjacent DPNSS PBXs and is inappropriate for the intervening QSIG network.
