Digi XBee 3 Cellular LTE-M User Manual page 261

API frames
Code Description
Interface not accepting frames. See
0x7D
0x7E A modem update is in progress. Try again after the update is complete.
0x80 Connection refused
0x81 Socket connection lost
0x82 No server
0x83 Socket closed
0x84 Unknown server
0x85 Unknown error
0x86 Invalid TLS configuration (missing file, and so forth)
0x87 Socket not connected
0x88 Socket not bound
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
User Data Relay - 0x2D.
Transmit (TX) Status - 0x89
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