defines a "MDN-based Message Center". In ANSI-41, MIN is a required parameter in the SMSREQ to the HLR. But in a MNP environment, the MC may not know the MIN, only the MDN. IS-841 adds MDN and makes MIN optional - one of these must be present in the SMSREQ.
IS-841 doesn't actually define how a message gets to the correct Message Center in the first place - e.g. for an inter-operator SMS, how does the originating network work out which network to send the message to - all it has is the MDN as the destination address which no longer identifies the operator. I guess it's possible to route this message as an inter-MC SMDPP addressed via GT, and have a clever STP in the middle perform a lookup on a Number Portability DataBase to determine the final destination.
In practice hovewer most people seem to use something like SMPP for inter-operator routing. So the lookup to the NPDB occurs in the IP world, not SS7. At this point I suppose it is not important whether the message is CDMA or GSM - the behaviour in SMPP should be the same...
hope this helps