Modem is reporting Disabled - SIM Inactive, signal = 0

When the cellular modem port in question can not successfully complete the modem initialization sequence, the SMS Statistics menu will display:

SIM Status Disabled - SIM Inactive
Signal Strength 0 (weak signal)

There are multiple causes for this situation:

A) SIM Card is locked with a security PIN.
B) Delays in the cellular registration process that can occur in certain situations or with certain SIM cards.
C) The iSMS feature "TCP Connection" is enabled and the unit is exposed to unexpected unwanted socket activity.

For items A & B, upon initialization sequence failure (error result codes reported by the modem) the iSMS server will restart the process - resulting in a constant initialization sequence until the problem is resolved or the port is disabled.

Resolutions:

A) Currently PIN enabled SIM cards are not supported. However, depending on the security implementation, disabling the PIN lock might be possible by using the +CPIN command or by the device/provider that enabled it.
B) Older iSMS Server firmware not tolerant to delays in +wind response. Update your iSMS SMS Server to 1.47 or higher.
C) Disable the "TCP Connection" option (per port), found in the "Network Setup > Cellular Modem" menu.


Examples: Use the "SMS Live Log" (Statistics & Logs > Log Traces menu) to confirm the condition.

A)SIM locked with PIN

Jul 7 09:35:52 [SEND] : AT+CFUN=0

Jul 7 09:35:54 [RECV] :
OK

Jul 7 09:35:54 [SEND] : Modem Reset successful
Jul 7 09:35:54 [SEND] : ATE0

Jul 7 09:35:57 [RECV] : ATE0
OK

Jul 7 09:35:57 [SEND] : AT+CMEE=1

Jul 7 09:36:00 [RECV] :
OK

Jul 7 09:36:00 [SEND] : AT+WIND=0

Jul 7 09:36:03 [RECV] :
OK

Jul 7 09:36:03 [SEND] : AT+CMGF=1

Jul 7 09:36:06 [RECV] :
OK

Jul 7 09:36:06 [SEND] : AT+CSDH=1

Jul 7 09:36:09 [RECV] :
+CMS ERROR: 311

Jul 7 09:36:12 [SEND] : AT+CSDH=1

Jul 7 09:36:15 [RECV] :
+CMS ERROR: 311

Jul 7 09:36:18 [SEND] : AT+CSDH=1

Jul 7 09:36:21 [RECV] :
+CMS ERROR: 311


B) 64K SIM Card used in version 1.44

Jan 1 00:00:04 modem: livelog: [SEND] : AT+CFUN=0
Jan 1 00:00:05 modem: livelog: [RECV] : AT+CFUN=0

ERROR

Jan 1 00:00:05 modem: livelog: [SEND] : Modem Reset successful
Jan 1 00:00:08 modem: livelog: [SEND] : ATE0
Jan 1 00:00:11 modem: livelog: [RECV] : ATE0

OK

Jan 1 00:00:11 modem: livelog: [SEND] : AT+CMEE=1
Jan 1 00:00:14 modem: livelog: [RECV] :
OK

Jan 1 00:00:14 modem: livelog: [SEND] : AT+CMGF=1
Jan 1 00:00:17 modem: livelog: [RECV] :
OK

Jan 1 00:00:17 modem: livelog: [SEND] : AT+CSDH=1
Jan 1 00:00:20 modem: livelog: [RECV] :
+CMS ERROR: 515

Jan 1 00:00:23 modem: livelog: [SEND] : AT+CSDH=1
Jan 1 00:00:26 modem: livelog: [RECV] :
+CMS ERROR: 515

Jan 1 00:00:29 modem: livelog: [SEND] : AT+CSDH=1
Jan 1 00:00:32 modem: livelog: [RECV] :
+CMS ERROR: 515

Jan 1 00:00:32 modem: livelog: [SEND] : AT+CFUN=0


C)TCP Socket access by malicious traffic. Connection opened and closed repeatedly. Each time the socket is opened, the txrx process for the port is killed. When the socket is then closed, the txrx process starts up again (+cfun=0).

Dec 14 15:57:46 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:57:47 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:57:48 txrx7-modem: livelog: [RECV] :
+CME ERROR: 515

OK

Dec 14 15:57:48 txrx7-modem: livelog: [SEND] : Modem Reset successful
Dec 14 15:57:50 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:57:51 txrx7-modem: livelog: [RECV] : ATE0

OK

Dec 14 15:57:51 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:57:52 txrx7-modem: livelog: [RECV] :
OK

Dec 14 15:57:53 txrx7-modem: livelog: [RECV] :
+WIND: 1

Dec 14 15:57:56 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:57:57 txrx7-modem: livelog: [RECV] :
OK

Dec 14 15:57:57 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:57:58 txrx7-modem: livelog: [RECV] :
OK

Dec 14 15:57:59 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:58:00 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:58:00 txrx7-modem: livelog: [RECV] :
ERROR

Dec 14 15:58:01 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:58:02 txrx7-modem: livelog: [RECV] :
ERROR

OK

Dec 14 15:58:02 txrx7-modem: livelog: [SEND] : Modem Reset successful
Dec 14 15:58:03 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:58:05 txrx7-modem: livelog: [RECV] : ATE0

OK

Dec 14 15:58:05 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:58:06 txrx7-modem: livelog: [RECV] :
OK

+WIND: 1

Dec 14 15:58:06 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:58:08 txrx7-modem: livelog: [SEND] : AT+CFUN=0
Dec 14 15:58:08 txrx7-modem: livelog: [RECV] :
OK

OK

Dec 14 15:58:08 txrx7-modem: livelog: [SEND] : AT+CMEE=1
Dec 14 15:58:09 txrx7-modem: livelog: [RECV] :
OK

Dec 14 15:58:09 txrx7-modem: livelog: [SEND] : Modem Reset successful
Dec 14 15:58:12 txrx7-modem: livelog: [SEND] : ATE0
Dec 14 15:58:13 txrx7-modem: livelog: [RECV] : ATE0

OK