SMSTools GSM Equipment and Network Error Codes

At work I’ve got a Nagios server setup to send text messages to my phone on critical notifications.  Lately something has been happening that causes sms notifications to fail.

In smsd.log I find that I get the follow error message:

+CME ERROR: 515 (device busy)

As root I’m able to reset the modem by doing this:
/bin/echo "AT+CFUN=1" > /dev/ttyUSB0
/etc/init.d/smstools restart

GSM Equipment related codes

Error Description
CME ERROR: 0 Phone failure
CME ERROR: 1 No connection to phone
CME ERROR: 2 Phone adapter link reserved
CME ERROR: 3 Operation not allowed
CME ERROR: 4 Operation not supported
CME ERROR: 5 PH_SIM PIN required
CME ERROR: 6 PH_FSIM PIN required
CME ERROR: 7 PH_FSIM PUK required
CME ERROR: 10 SIM not inserted
CME ERROR: 11 SIM PIN required
CME ERROR: 12 SIM PUK required
CME ERROR: 13 SIM failure
CME ERROR: 14 SIM busy
CME ERROR: 15 SIM wrong
CME ERROR: 16 Incorrect password
CME ERROR: 17 SIM PIN2 required
CME ERROR: 18 SIM PUK2 required
CME ERROR: 20 Memory full
CME ERROR: 21 Invalid index
CME ERROR: 22 Not found
CME ERROR: 23 Memory failure
CME ERROR: 24 Text string too long
CME ERROR: 25 Invalid characters in text string
CME ERROR: 26 Dial string too long
CME ERROR: 27 Invalid characters in dial string
CME ERROR: 30 No network service
CME ERROR: 31 Network timeout
CME ERROR: 32 Network not allowed, emergency calls only
CME ERROR: 40 Network personalization PIN required
CME ERROR: 41 Network personalization PUK required
CME ERROR: 42 Network subset personalization PIN required
CME ERROR: 43 Network subset personalization PUK required
CME ERROR: 44 Service provider personalization PIN required
CME ERROR: 45 Service provider personalization PUK required
CME ERROR: 46 Corporate personalization PIN required
CME ERROR: 47 Corporate personalization PUK required
CME ERROR: 48 PH-SIM PUK required
CME ERROR: 100 Unknown error
CME ERROR: 103 Illegal MS
CME ERROR: 106 Illegal ME
CME ERROR: 107 GPRS services not allowed
CME ERROR: 111 PLMN not allowed
CME ERROR: 112 Location area not allowed
CME ERROR: 113 Roaming not allowed in this location area
CME ERROR: 126 Operation temporary not allowed
CME ERROR: 132 Service operation not supported
CME ERROR: 133 Requested service option not subscribed
CME ERROR: 134 Service option temporary out of order
CME ERROR: 148 Unspecified GPRS error
CME ERROR: 149 PDP authentication failure
CME ERROR: 150 Invalid mobile class
CME ERROR: 256 Operation temporarily not allowed
CME ERROR: 257 Call barred
CME ERROR: 258 Phone is busy
CME ERROR: 259 User abort
CME ERROR: 260 Invalid dial string
CME ERROR: 261 SS not executed
CME ERROR: 262 SIM Blocked
CME ERROR: 263 Invalid block
CME ERROR: 772 SIM powered down

GSM Network related codes:

Error Description
CMS ERROR: 1 Unassigned number
CMS ERROR: 8 Operator determined barring
CMS ERROR: 10 Call bared
CMS ERROR: 21 Short message transfer rejected
CMS ERROR: 27 Destination out of service
CMS ERROR: 28 Unindentified subscriber
CMS ERROR: 29 Facility rejected
CMS ERROR: 30 Unknown subscriber
CMS ERROR: 38 Network out of order
CMS ERROR: 41 Temporary failure
CMS ERROR: 42 Congestion
CMS ERROR: 47 Recources unavailable
CMS ERROR: 50 Requested facility not subscribed
CMS ERROR: 69 Requested facility not implemented
CMS ERROR: 81 Invalid short message transfer reference value
CMS ERROR: 95 Invalid message unspecified
CMS ERROR: 96 Invalid mandatory information
CMS ERROR: 97 Message type non existent or not implemented
CMS ERROR: 98 Message not compatible with short message protocol
CMS ERROR: 99 Information element non-existent or not implemente
CMS ERROR: 111 Protocol error, unspecified
CMS ERROR: 127 Internetworking , unspecified
CMS ERROR: 128 Telematic internetworking not supported
CMS ERROR: 129 Short message type 0 not supported
CMS ERROR: 130 Cannot replace short message
CMS ERROR: 143 Unspecified TP-PID error
CMS ERROR: 144 Data code scheme not supported
CMS ERROR: 145 Message class not supported
CMS ERROR: 159 Unspecified TP-DCS error
CMS ERROR: 160 Command cannot be actioned
CMS ERROR: 161 Command unsupported
CMS ERROR: 175 Unspecified TP-Command error
CMS ERROR: 176 TPDU not supported
CMS ERROR: 192 SC busy
CMS ERROR: 193 No SC subscription
CMS ERROR: 194 SC System failure
CMS ERROR: 195 Invalid SME address
CMS ERROR: 196 Destination SME barred
CMS ERROR: 197 SM Rejected-Duplicate SM
CMS ERROR: 198 TP-VPF not supported
CMS ERROR: 199 TP-VP not supported
CMS ERROR: 208 D0 SIM SMS Storage full
CMS ERROR: 209 No SMS Storage capability in SIM
CMS ERROR: 210 Error in MS
CMS ERROR: 211 Memory capacity exceeded
CMS ERROR: 212 Sim application toolkit busy
CMS ERROR: 213 SIM data download error
CMS ERROR: 255 Unspecified error cause
CMS ERROR: 300 ME Failure
CMS ERROR: 301 SMS service of ME reserved
CMS ERROR: 302 Operation not allowed
CMS ERROR: 303 Operation not supported
CMS ERROR: 304 Invalid PDU mode parameter
CMS ERROR: 305 Invalid Text mode parameter
CMS ERROR: 310 SIM not inserted
CMS ERROR: 311 SIM PIN required
CMS ERROR: 312 PH-SIM PIN required
CMS ERROR: 313 SIM failure
CMS ERROR: 314 SIM busy
CMS ERROR: 315 SIM wrong
CMS ERROR: 316 SIM PUK required
CMS ERROR: 317 SIM PIN2 required
CMS ERROR: 318 SIM PUK2 required
CMS ERROR: 320 Memory failure
CMS ERROR: 321 Invalid memory index
CMS ERROR: 322 Memory full
CMS ERROR: 330 SMSC address unknown
CMS ERROR: 331 No network service
CMS ERROR: 332 Network timeout
CMS ERROR: 340 No +CNMA expected
CMS ERROR: 500 Unknown error
CMS ERROR: 512 User abort
CMS ERROR: 513 Unable to store
CMS ERROR: 514 Invalid Status
CMS ERROR: 515 Device busy or Invalid Character in string
CMS ERROR: 516 Invalid length
CMS ERROR: 517 Invalid character in PDU
CMS ERROR: 518 Invalid parameter
CMS ERROR: 519 Invalid length or character
CMS ERROR: 520 Invalid character in text
CMS ERROR: 521 Timer expired
CMS ERROR: 522 Operation temporary not allowed
CMS ERROR: 532 SIM not ready
CMS ERROR: 534 Cell Broadcast error unknown
CMS ERROR: 535 Protocol stack busy
CMS ERROR: 538 Invalid parameter