View source for Mobile Data Connection Troubleshooting

__TOC__

==Summary==
This is a quick guide to help in the debugging process of a router if encounters issues with mobile data connection.

==Preparation==
* First, to establish a data connection only through mobile module on RUT, you need connect to router via CLI/SSH (use SSH software such as PuTTY client):
 CLI/SSH username: root
 CLI/SSH password: <your router’s password>
----
* Connect to mobile module of the router:
 ... 
 root@Teltonika:~# ifdown ppp
 root@Teltonika:~# /etc/init.d/gsmd stop
 root@Teltonika:~# microcom /dev/modem_cmd
 +QCSQ: "LTE",47,-75,166,-10
 +QCSQ: "LTE",47,-75,161,-10
 +CREG: 1,"008B","012CD17",7
 ...
----
* You probably won't see anything when you type commands, and that’s because the screen echo may be disabled. '''ATE1''' command will enable it so that you can see what you write. 
 ...
 ATE1
 OK
 ...
----
* Use commands '''AT+QCSQ=0''' and '''AT+CREG=0''' to stop showing unnecessary output:
 ... 
 at+qcsq=0
 OK
 at+creg=0
 OK
 ...
----
* Check communication (wait for the module to respond '''OK'''):
 ... 
 AT
 OK
 ...
----

==Debugging process==
* If PIN is required, initialize modem with your PIN code:
 ...
 AT+CPIN="xxxx"
 ...
----
* Use command '''AT+CPIN''' to query SIM card status:
 ...
 AT+CPIN?
 +CPIN: READY
 ...
'''Note:''' reboot the module if it fails to identify SIM
----
*Use command '''AT+CREG''' to check GSM connection:
 ...
 AT+CREG?
 +CREG: 0,1
 OK
 ...
'''Note:''' OK means that the module has registered on CS domain service
----
* Use command '''AT+CGREG''' to check PS Service:
 ...
 AT+CGREG?
 +CGREG: 0,1
 OK
 ...
'''Note:''' OK means that the module has registered in UMTS/LTE network 
----
* Use command '''AT+QICSGP''' to configure APN, user name, password and auth type:
 AT+QICSGP=<contextID>[,<context_type>,<APN>[,<username>,<password>)[,<authentication>]]]

''<context type>'' The protocol type (1 – IPV4; 2 – IPv6);

''<context id>'' The range is 1-16;

''<authentication>'' The authentication methods (0 – NONE; 1 – PAP; 2 – CHAP; 3-PAP or CHAP).

Example: '''AT+QICSGP=1,1,"APN_Name","","",1'''
 ...
 AT+QICSGP=1,1"bangapro","","",1
 OK
 ...
----
* Use command '''AT+QIACT=<contextID>''' to activate a PDP context:
 ...
 AT+QIACT=1
 OK
 ...
----
* Use command '''AT+QIACT?''' to query IP Address of the PDP context:
 ...
 AT+QIACT?
 +QIACT: 1,1,1,"88.77.66.55"
 OK
 ...
'''Note:''' try and activate a PDP context a few times. If failed, then reboot the module.
----
* Use command '''AT+QIOPEN''' to open connection:
 ...
 AT+QIOPEN
 OK
 ...
'''Note:''' if failed – deactivate PDP context - use command '''AT+QIDEACT=<context ID>''' to deactivate PDP context.
----
* Use command '''AT+QPING''' to ping a Remote Server:
 ...
 AT+QPING=1,"8.8.8.8"
 OK
 +QPING: 0,"8.8.8.8",32,54,255
 +QPING: 0,"8.8.8.8",32,30,255
 +QPING: 0,"8.8.8.8",32,35,255
 +QPING: 0,"8.8.8.8",32,34,255
 +QPING: 0,4,4,0,30,54,37
 ...

''1'' –The context ID. The range is 1-16;

''8.8.8.8'' - The host address in string type.

'''Note:''' if ping a remote server successfully, response is '''OK''' (means that the module works properly). If there is any error, response is '''ERROR''' (means the problem is in the module).

==Example for the provided configuration==
 ...
 root@Teltonika:~# ifdown ppp
 root@Teltonika:~# /etc/init.d/gsmd stop
 root@Teltonika:~# microcom /dev/modem_cmd
 +QCSQ: "LTE",47,-75,166,-10
 +QCSQ: "LTE",47,-75,161,-10
 +QCSQ: "LTE",47,-75,156,-10
 +CREG: 1,"008B","012CD17",7
 AT+QCSQ=0
 OK
 +CREG: 1,"008B","012CD0D",7
 +CREG: 1,"008B","012CD17",7
 AT+CREG=0
 OK
 AT
 OK
 ...

 ...
 AT+CPIN?
 +CPIN: READY
 OK
 AT+CREG
 OK
 AT+CREG?
 +CREG: 0,1
 OK
 AT+CREG
 OK
 AT+CGREG?
 +CGREG: 0,1
 OK
 AT+QICSGP=1,1"bangapro","","",1
 OK
 AT+QIACT=1
 OK
 AT+QIACT?
 +QIACT: 1,1,1,"88.77.66.55"
 OK
 ...

 ...
 AT+QIOPEN
 OK
 AT+QPING=1,"8.8.8.8"
 OK
 +QPING: 0,"8.8.8.8",32,54,255
 +QPING: 0,"8.8.8.8",32,30,255
 +QPING: 0,"8.8.8.8",32,35,255
 +QPING: 0,"8.8.8.8",32,34,255
 +QPING: 0,4,4,0,30,54,37
 ...

[[Category:FAQ]]