OsmoMSC's GSUP client doesn't send CN domain to the HLR
hence all osmo-msc clients are seen as PS clients.
That will lead to client identifications being stored in sgsn_number instead of vlr_number.
It may be the case that in classic GSM the CN domain indicator is optional, as CS
existed before PS. So in absence of the indicator, as HLR I would always assume it's CS.
In GSUP we explicitly specify that a lack of CN domain indicator means PS...
probably from the time it still was the GPRS Subscriber Update Protocol.