The aim is to deliver welcome SMS when subscriber appears inside a dedicated cell. Top layer logic varies the behaviour of the system depending on the history and different lists where subscribers' number might be mentioned.
Equipment contains number of probes which are capable of monitoring a-bis interface (BSSAP) and a server which is connected to an MSC by means of MAP (over SS7 stack or SIGTRAN).
Probe detects the appearance of new subscribers inside the area. There can be various subscriber identifiers on the a-bis interface, but in most cases temporary mobile subscriber identities (TMSI) are used, that was the main obstacle while building a solution.
Server is responsible for different transformations of subscriber identifiers in order to check against different lists and deliver messages.