It seems you are working in R10 Release and AXE810 Node.
AM I correct ?
In R10 They divided the SMS-Legs further for Traffic Calculation and Charging Purpose.Read it in ALEX.
MSMO is for MS to SMS-IWMSC( MSC).
MSMT is for SMS-GMSC to MS.
GSMS is for SC to SMS-GMSC
IWSMS is for SMS-IWMSC to SC.
Rgds
* You will soon get a mail from Me.
Rgds