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Sierra GL7600 4G modem
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November 26, 2017
9:40 am

Hi Henk,

Again, please accept my gratitude to your quick response.

Despite setting the 'SMSOverGPRS' property to 'True', it still does not work.

I guess I finally had enough and will have to forgo Sierra 4G LTE techonologiy.

November 23, 2017
3:07 pm
Henk Helmantel
Forum Posts: 1502
Member Since:
May 28, 2013
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Interesting. I was not aware of this.

You can try if setting the 'SMSOverGPRS' property to 'True' in the advanced settings of the GSM Modem Gateway helps. This setting sets 'AT+CGATT=1' so the modem won't break the connection and it instructs the modem to send the SMS messages over the internet connection.

Regards, Henk

November 23, 2017
5:25 am

Hi Henk,

The stubborn me simply refused to give up. I had lengthly communication with Sierra and I think we are getting closer.

The GL7600 is a 4G LTE modem. In case of LTE, it is a packet only technology.

In the logs we can see that the host sending the command AT+CGATT=0. Since LTE is a packet only technology, PS detach means deregistration. How can we remove the command AT+CGATT=0 ?

November 20, 2017
12:15 pm

Dear Henk,

I tried the 1st suggestion of " In 'Normal' and 'Enhanced' mode: Set the 'ModemInitializationEnd' property to 'AT+CMMS=0'. It still does not work and it returned a "300, Error: Unknown error after PDU sent".

I also tried the 2nd suggestion of " In 'BasicPDUMode': Set the 'ModemInitializationBeginning' property to 'AT+CNMI=1,0,0,1'. "
The message was send through, but again there is no Delivery Report. There is only a Send Report.

At the outset, I must indicate my appreciation for your help and dare not further impose anymore trouble on you.

Regards with Best Wishes,

November 17, 2017
2:13 pm
Henk Helmantel
Forum Posts: 1502
Member Since:
May 28, 2013
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You can try the following two suggestions. If they do not work then I do not know what else to suggest.

1. In 'Normal' and 'Enhanced' mode: Set the 'ModemInitializationEnd' property to 'AT+CMMS=0'.

2. In 'BasicPDUMode': Set the 'ModemInitializationBeginning' property to 'AT+CNMI=1,0,0,1'.

The first setting disables fast continuous SMS sending in 'Normal' and 'Enhanced' mode. This setting can cause problems in some modems or mobile networks. The second setting instructs the modem to forward delivery reports directly to the serial port instead of storing them on the SIM card. This is the method that is used in 'Normal' compatibility mode to get the delivery reports from the modem.

Regards, Henk

November 17, 2017
5:29 am

Below is the relevant communication log :

2017/11/17 12:23:04.914 > AT+CMGF=0
2017/11/17 12:23:04.945 < OK
2017/11/17 12:23:04.945 > AT+CNMI=1,0,0,1
2017/11/17 12:23:04.976 < OK
2017/11/17 12:23:04.976 > AT+CSCA?
2017/11/17 12:23:05.029 < +CSCA: "+6596845999",145
2017/11/17 12:23:05.045 < OK
2017/11/17 12:23:05.045 > AT+COPS=3,2
2017/11/17 12:23:05.076 < OK
2017/11/17 12:23:05.076 > AT+COPS?
2017/11/17 12:23:05.113 < +COPS: 0
2017/11/17 12:23:05.129 < OK
2017/11/17 12:23:05.129 > AT+COPS=3,0
2017/11/17 12:23:05.160 < OK
2017/11/17 12:23:05.160 > AT+COPS?
2017/11/17 12:23:05.191 < +COPS: 0
2017/11/17 12:23:05.213 < OK
2017/11/17 12:23:05.213 > AT+CMMS=2
2017/11/17 12:23:05.244 < OK
2017/11/17 12:23:05.244 > AT+CSQ
2017/11/17 12:23:05.276 < +CSQ: 7,2
2017/11/17 12:23:05.291 < OK
2017/11/17 12:23:05.291 > AT+CREG?
2017/11/17 12:23:05.329 < +CREG: 0,2
2017/11/17 12:23:05.344 < OK
2017/11/17 12:23:05.360 > AT+CMGL=4
2017/11/17 12:23:06.441 < OK
2017/11/17 12:23:06.457 > AT+CMGS=20
2017/11/17 12:23:06.488
2017/11/17 12:23:06.488 > 0691566948959931040A9156799630330000AA08F4F29C0E92C964
2017/11/17 12:23:06.592 < +CMS ERROR: 287
2017/11/17 12:23:06.593 >
2017/11/17 12:23:06.733 - Serial port closed.

November 17, 2017
4:49 am

Hello Henk,

I tried setting the 'ModemRebootTime' property to 60 seconds AND also setting 'RebootBeforeInitialization' property to 'False'. But it does not work. I still am unable to send out sms in both Normal and Enhance book.

So far, the only thing that work is to set the GSM modem CompatibilityMode to 'BasicPDUMode' . But by setting to 'BasicPDUMode', there is no delivery report.

Any other possible solutions ?

November 16, 2017
11:47 am
Henk Helmantel
Forum Posts: 1502
Member Since:
May 28, 2013
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Hello Mike,

The most likely reason that the modem only works properly in 'BasicPDUMode' is that Diafaan SMS Server reboots the modem in 'Normal' and 'Enhanced' mode before initializing the modem. Rebooting the modem takes time and for some modems or mobile networks the time that Diafaan SMS Server waits after the reboot before sending the first message is too short to allow the modem to re-connect to the mobile network.

You can increase the wait time after a reboot or disable the reboots completely. To change the reboot wait time, open the 'Advanced' GSM Modem Gateway settings and increase the 'ModemRebootTime' property to 45 or 60 seconds. To disable the reboots, set the 'RebootBeforeInitialization' property to 'False'.

Diafaan SMS Server handles delivery reports differently in 'Normal' and 'Enhanced' mode. In theory both methods should work with all modems that conforms to the standards, in practice delivery reports for some modems only work well in 'Normal' mode and for other modems only in 'Enhanced' mode. And some modems require a specific setting for delivery reports to work.

Regards, Henk

November 16, 2017
8:09 am

Dear Henk

1. I have been trying Diafaan SMS Server with Sierra GL7600 (4G modem).

2. Using other 3G modem, I can sent out sms and always get prompt 201 Delivery Report almost immediately without fail.

3. Using Sierra GL7600, I am unable to send any sms. The error says :

Status : 300 Error : Unknown error after PDU sent.
Error : 287 CMS error: Unknown or manufacturer specific error

Other Symptoms 1
4. Using Sierra GL7600 4G modem, I can only send out SMS if I were to change GSM Modem  Compatibility Mode from Normal to BasicPDUMode, but there will be a 200 Send Report instead of a 201 Delivery Report.

A 201 Delivery Report will be crucial to our plans to roll out and buy this software.

Other Symptoms 2
5. The Sierra technician guy also tried to troubleshoot. If the modem is working well, it should be blinking green in colour. However, the modem LED is permanently lighted up which shows that the modem cannot register in with the mobile network.

6. Please help and I'd be most grateful for your guidance

Mike Cheng

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