Digi XBee 3 Cellular LTE-M User Manual page 176

Extended Socket frames
When a Socket Status indicating a connection close is received, the socket ID will have been de-
allocated by the XBee and no further operations are possible or necessary using that ID.
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
Extended Socket example: TCP Listener
176