An LSU (Local SCCP User) is an application configured with a subsystem number to handle Rt-on-SSN traffic for a local signaling point code hosted on an MP server.
Adding, deleting, or changing the status of an LSU affects the routing to configured Local SCCP Users. SCCP is notified when an operator creates a local subsystem via the GUI and assigns a Local SCCP User to the local subsystem. This assignment entry is added to SCCP's internal database with a default status of Disabled. The assignment enables SCCP to track the status of locally configured LSUs for messages that are routed on the SSN.
The SS7/Sigtran > Configuration > Local SCCP Users GUI page contains a row for each SS7 application hosted by SS7-MP servers. The fields in each row indicate which SSN is associated with an application.