Merlin card and Data SMS reception

[Carretero]

Hi for all,
In the past, I was using a Novatel U530 to receive Data SMS (MMS notifications, WapPush notifications) and it works fine. I read the SMS with a C++ application that sends AT commands in the modem serial port (AT+CMGF,AT+CMGL).
This method fails with U630 fw14.2(but not 12.0) and U740 fw15.4 Cards. With these cards I can read text sms only, it seems that the card filter some SMS messages.

Are there any change in fw 12.0->14.2 that disables this feature?
Are there any other method to read SMS in these cards?

Thanks in advance.

 

[Carretero]

More information

I have activated the asynchronous SMS reception notification (CNMI) and I can see the Data SMS reception as:

+CMTI: "SM",-1
or
+CMTI: "SM",-254

Before this CMGL response is:

AT+CMGL=4
OK
There is no data message into SM memory.(Selected for read with CPMS)

If I send a text SMS I see the normal indication +CMTI: "SM",0 and sms is stored into index 0 of memory.

Where is my Data SMS? Which is the meaning of index -1 or -254?

Heeelp, please!!