This kind Signalling System is little older than combare to C7/SS7.
In R2 You have to handle two kind of Signalling.
1.Line Signalling
2.Register Signalling
Line Signalling used used to hadle the SEIZURE and CLEARING of Circuits.Register-Takes care Subcriber Sigannls.
First Line Signalling after Seizyre Register Signalling will Start.