React to IMSI Attach but not PERIODIC

Hi All, I have a use case where I'd like to react to MS connecting to the network, that is on initial IMSI ATTACH. We already have the SMPP alert notification mechanism which can be used, but unfortunately in SMPP the ms_availability_status only has 3 posible values in the spec: 0: Available 1: Denied 2: Unavailable. So currently if I react to status 0, this would also happen on periodic LURs I could keep state separately but that sounds prone to errors. The external process reacting to the alert notification could try somehow to get the previous status from HLR or database, but that sounds like a race condition. One possibility might be to extend this with a further custom value 3: Available (Initial Attach) or some such? Any thoughts?