Is my SIM card faulty or is my provider annoying me?

gprs at-command ppp sim-card
morandg picture morandg · Dec 20, 2011 · Viewed 8.8k times · Source

I'm trying to establish a PPP connection using pppd and AT Commands. This usually works fine with a SIM card of my local provider. However, I received a card from a friend that is living in Germany and I wanted to give it a try from Switzerland but I have a very strange behavior.

First I cannot activate the error message (AT+CMEE), I always get the error message "ERROR" despite I activated the full verbose previously (AT+CMEE=2). This commands works with my local provider SIM card ...

Then if I check the network status:

AT+CGREG?
+CGREG: 1,3

Believing the "3", this means "Registration denied".

When I try to attach or detach, I always have an error without more explanation (Despite AT+CMEE=2):

AT+CGATT=0
ERROR
AT+CGATT=1
ERROR
AT+CGATT?
+CGATT: 0

OK

I can send SMS with AT commands! Putting the SIM card in a phone, I cannot establish any call!

So is it possible to send SMS without the need to register to the network? Is it possible that error message reporting is deactivated on the SIM card? I'm wondering if this is a problem of configuration, a problem of the SIM card or a problem of provider...

Edit

If this could help someone. I tried to send an SMS when I'm detached from the network with my working SIM card, it works! Believing this website I guess my friend didn't pay the bill or my local network provider refuses me to use its network ...

Answer

SKi picture SKi · Dec 29, 2011

Probably roaming of circuit switched data (GSM) is allowed. And roaming of GPRS service is not allowed.

AT+CGREG? returns status of GPRS registration.

AT+CREG? returns status of network registration (GSM/UMTS). Try command:

 AT+CREG?

It probably will return 5 (Registered, roaming).

SMS message sending works because it does not need GPRS. Attach and +CGREG stuff are all for GPRS.

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