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  • #10691 Reply



    I bougth an usb modem to attach it to the telephone line with no sim.
    I am trying to make a data call, so when I call the phone number it says me “CONNECT 9600” but I am not able to writte any more, even I can not use “+++” and neither “ATH” to finalize the call.

    Could be because I am using a modem with no SIM?

    Most of the AT commands does not work with my modem.


    #10694 Reply


    Voice or data call will not go through without a valid SIM in the USB modem. However you should get responses for AT commands even if the SIM is not present.

    You can use the AT Command Tester tool to get some diagnostic info or use hyperterminal to check as below,

    //Send AT+CPIN? command. If the SIM card is ready, should you get the response as below.
    //Check the registration status with AT+CREG? command. If it is registered in home network, you should see the respnse like below. If it is roaming, the response will be +CREG: 0,5.
    +CREG: 0,1
    //Then check the attach status. Only if the device is registered, it can attach to the network
    +CGATT: 1

    The device should be sucessfully registered and attached before you can make a data call. Then you need to check if your connection profiles are setup properly. You can read those in the ‘Data Call’ tab of AT Command Tester tool .

    #10695 Reply


    Hello again,

    I think I have not explained myself well, I have an usb modem like this:

    So It has not SIM slot, I have to connect It to my home phone line. I can make calls, If call to my movile phone number, rings are raised right, and if make a datacall to another device with the ATD command it says me “CONNECT 9600” as expected, It is just after the other device pick up the call, I can not use any command like “+++”, “AT” or “ATH”.

    The commands I meant are not working are most of the other normal AT commands like those you told me to check: AT+CSQ, AT+CREG, AT+CPIN (I have no SIM), AT+CGAT, I think that it is because the modem has no sim.

    Many thanks.

    #10697 Reply


    I beleive “+++” escape sequence should work as explained in the link below..
    Escape Code Sequence
    When the modem has established a connection and has entered on-line data mode, it is
    possible to break into the data transmission in order to issue further commands to the modem
    in an on-line command mode. This is achieved by the DTE sending to the modem a sequence
    of three ASCII characters specified by register S2.The default character is ‘+ ‘. The maximum
    time allowed between receipt of the last character of the three escape character sequence from
    the DTE and sending of the OK result code to the DTE is controlled by the S12 register.

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