It allows multiple system to co-exist on the same IP network.
It is also used as http port on localhost to access TBToolpack WebPortal.(ie: http://localhost:12358)
The SystemId is also the TBX_GW_PORT UDP port use to control the Tmedia units.
Range: 12358-12458 Default: 12358 (TelcoBridges strongly recommends that this setting be left at its default value)
All TBToolpack installations part of the same system must use the same SystemId.