Multi-Tech Systems MMCModem GPRS (MTMMC-G) - Manual (Page 175)

Appendix A – Result Codes, Failure Causes, Other Tables
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 175
Continued: Specific Error Result Codes
Meaning Results from the following commands
544 CMUX connection Timeout (no answer from the remote); i.e., no
DLCO opened response. +CMUX
545 A CMUX session has been started on a physical UART, and the
user tries to start another CMUX session on another physical
UART. The error, +CME ERROR: 545 is raised on the UART
where AT+CMUX command is trying to be started again. +CMUX
546 Emergency call is not allowed without SIM +COPS
547 Emergency call is allowed without SIM +COPS
548 No flash objects to delete +WOPEN
549 The phone number of the requested phonebook entry is empty ATD>[;],ATD>[;]
550 Unable to resize the Application & Data storage place since the
new required size would overlap with the current Open AT
®
application storage place
+WOPEN
551 Service abort request has failed AT+WAC
552 Unsolicited responses for autodiag or charge indication are
already activated on another port +WDIAG, +WBCM