Unable to activate a PDP context over GPRS

IoT Modules Legacy HL Series
1

Hello, I’m working with the HL6528 modem and AirPrime HL Series Development Kit. I am unable to activate a PDP context over GPRS or establish a UDP connection. I am also seeing what appears to be issues with the network connectivity. The network connectivity could be the reason for the other issues. The one success I have had is that I’ve been able to send SMS messages from the modem when it does register with the network.

I have details of the AT commands and responses below.
-Jason

• Network registration is intermittent
o The modem is able to register with the network (AT&T) but the registration is intermittent and often get a status of “registration denied”. I know the issue is NOT with the SIM card or network because if I use the same SIM card in a modem from another manufacturer, then network registration is fine (see modem serial log at the end of the e-mail)

IIII▒▒▒▒▒▒▒▒
+CREG: 2

+CREG: 0

+CREG: 2

+CREG: 1,“0BCE”,“F6EC”

+CREG: 1,“0BDC”,“0551”
at+csq
+CSQ: 14,99

OK
at+creg?
+CREG: 2,1,“0BDC”,“0551”

OK

+CREG: 0

+CREG: 3

+CREG: 0
at+cops?
+COPS: 0

OK
at+cops=?
+COPS: (2,“AT&T”,"",“310410”),(1,“T-Mobile”,"",“310260”),(0,1,4),(0,2)

OK

• Unable to activate PDP context for GPRS communication
o I can define a PDP context but am unable to activate it

IIII▒▒▒▒▒▒▒▒
+CREG: 2

+CREG: 0

+CREG: 2

+CREG: 1,“0BDC”,“0551”
at+csq
+CSQ: 17,99

OK
at+cgdcont=1,“IP”,“isp.cingular”
OK
at+cgact=1,1
ERROR

+CREG: 1,“0BDC”,“0553”
at+csq
+CSQ: 14,99

OK
at+creg?
+CREG: 2,1,“0BDC”,“0553”

OK

• Unable to establish UDP connection
o I can configure the GPRS connection but am unable to configure the UDP connection

IIII▒▒▒▒▒▒▒▒
+CREG: 2

+CREG: 0

+CREG: 2

+CREG: 1,“0BCE”,“0020”
at+csq
+CSQ: 10,99

OK
at+csq
+CSQ: 10,99

OK
at+creg?
+CREG: 2,1,“0BCE”,“0020”

OK
AT+KCNXCFG=0,“GPRS”,“isp.cingular”,"","",“208.77.56.93”,
OK

+CREG: 1,“0BDC”,“0551”
AT+KUDPCFG=0,0,290
NO CARRIER
+KUDP_NOTIF: 1,0

+CREG: 1,“0BCE”,“F6EC”

• Other Modem Network Registration (using same SIM card as HL6528)

+CREG: 0

+CGREG: 0

+CREG: 2

DISCONNECT
at+csq
+CSQ: 99,99

OK
at+csq
+CSQ: 99,99

OK
at+csq
+CSQ: 99,99

OK

+CREG: 1,“0BDC”,“0551”
at+csq
+CSQ: 17,99

OK
at+csq
+CSQ: 17,0

OK
at+csq
+CSQ: 16,1

OK

+CREG: 1,“0BDC”,“0553”
at+csq
+CSQ: 17,1

OK

+CREG: 1,“0BDC”,“0551”

+CREG: 1,“0BDC”,“0553”

+CREG: 1,“0BDC”,“0551”

+CREG: 1,“0BDC”,“0553”

2

Hi,
I am able to activate PDP context using AT+CGACT command and is able to do a dial up connection :smiley:
Can you check the error using AT+CMEE=1 command? Also can you check with some other SIM card?

Thanks,
Rex

3

Hi Rex,
I believe the issue comes down to the SIM card. I have tried 3 SIM cards. Only 1 of 3 registers to the network with the HL6528 modem. (All 3 SIM cards register to the network on another modem we’re using. When I get a good network registration, I can activate PDP context and successfully send UDP data.) It could be an issue with the SIM card contacts or the SIM circuitry on the HL Dev Kit. Any thoughts or things I could try to see if the SIM card is correctly detected?

I tried using the +KSIMDET Command, but it is not working. On the HL Dev Kit, I have jumpers installed on CN801, CN600, and CN803 to enable both SIM1/2 and insertion detection on both. However, using the KSIMDET command to enable detection only returns CME ERROR: 4 Operation not supported result.

AT+KSIMDET=?
+KSIMDET: (0-1),(1-8),(0-1)

OK
AT+KSIMDET?
+KSIMDET: 0,1,0
+KSIMDET: 0,1,1

OK
at+ksimdet=1,1
+CME ERROR: 4
at+ksimdet=1,2
+CME ERROR: 4

-Jason