It is possible to have Optimal Routing.Now there are lot of products for this.
But first clear your doubts in Normal MO Call and MT Call.
MO Call :
MS in MSC-1 (Serving )
MS A —> MSC -1 =As per B-Number The can be routed to
In case if it is Mobile Number the B-No is analysed first.
Note this VV Important : “If the MSC Founds that the B-Number is belongs to same PLMN then it will route to GMSC ” as per Routing program.GMSC May integrated or may be in some other Place.
Only if the B-Number belongs to same network.This is found out in B-Number ANALYSIS..etc..etc..ok
If the B-Number belongs to some other PLMN network then the call may go through Direct Route between Serving MSC amd Other PLMN or Through PSTN ( In India ).
MT Call :
MT Call scene starts whenevr a call reaches GMSC.It may come from PSTN Other PLMN or Integarted MSC or From Same PLMN MSC Through Inter MSC Links.
Then onwards MT Call scene starts up.
Understand them Separately.Never Mix Them.