DataKinetics DSC110 User Manual page 12

1.2.2 Access Signalling
On the access side the converter supports up to 30 access side signalling links.
Layers 2 and 3 of the access side signalling protocol are implemented on the
signalling cards. Access side call control is implemented on the central processor.
Currently the converter supports the following access signalling:
ETSI Euro ISDN (Network Side)
ETSI Euro ISDN (User Side)
North American ISDN (Network Side)
North American ISDN (User Side)
ETSI QSIG
DPNSS
1.2.3 Signalling Conversion
Signalling Conversion takes place on the central processor card. The signalling
conversion functionality receives messages from the User Part on the SS7 side
and from the ISDN/DPNSS call control module on the access side. It performs the
necessary conversion selecting a suitable outgoing route and controlling the voice
paths as necessary before sending the signalling messages to either the User
Part module or the ISDN/DPNSS call control module.
1.2.4 Configuration Model
The basic unit of configuration is a circuit group. All configured circuits (or
devices) on an access side signalling link are configured into a circuit group. On
the SS7 side groups of not more than 32 circuits (or devices) are configured into
circuit groups. It is usual (although not essential) for a circuit group to contain all
the voice circuits on an E1/T1 port.
When an incoming call arrives at the converter the decision on how to process the
call comes from the Point of Origin configuration data. Each circuit group is
assigned a single point of origin (although a single point of origin may be used by
several circuit groups). The point of origin data contains several parameters which
allow for the addition or removal of digits to both the calling and called party
numbers and also specify either a Digit Analysis Index which is used to carry out
(dynamic) routing of the call or a Default outgoing route when routing is not
required (this is always true in signalling only mode).
The digit analysis index is used to select a suitable outgoing route on which the
call should be placed. This may be one of several outgoing routes selected on the
basis of the dialled digits contained in the called party number.
The outgoing route may have an associated Next route. If present the next route
provides the ability to route to a different destination if all devices on the first
outgoing route are unavailable or an indication has been received from a
subsequent exchange indicating a problem. Since a next route is a route in its own
right a chain of routes can be formed to find the best route to a destination.
The outgoing route data contains further parameters that allow the called and
calling party numbers to be modified and a Hunt mode that controls the algorithm
used to select an outgoing circuit.
Finally the hunt sequence associated with the outgoing route is used to select a
circuit group for the outgoing call.
DataKinetics DSC110 / DSC210 User Manual Issue 12 Page 12