When a device is turning off or disconnecting from the network, it should send an AT command sequence to deregister from this network.
"Attached" Status in the EUI
Sometimes a device does not have the possibility to send AT command sequence to deregister from a network eg. in case of power failure or reset connectivity from the EMnify User Interface.
In this situation, the status in the EUI will remain "Attached" as an indication of the last network operator to which the endpoint was last connected to.
It will remain "Attached" until the EMnify Core Network receives a cleanup update (the event shown in the EUI will be "Purge Location) from the roaming partner.
Purging means to delete the subscriber data in the visited roaming network.
Purge location or Purge Mobile Subscriber is an event which occurs on the VLR (Roaming partner equipment). A VLR may purge the subscriber data for an Mobile Subscriber which has not established radio contact for a period determined by the roaming network operator.
Basically, this happens when a Mobile Device is idle for a long period of time. The VLR(visited Network) shall inform the HLR (EMnify) of the purging. The retention or removal of Mobile Subscriber data is depending on roaming partner configuration.