# ZTE MF 823 (Megafon M100-3) 4G Modem

## Device Identification

Examine the output of lsusb. You should get:

    $ Bus 002 Device 018: ID 19d2:1405 ZTE WCDMA Technologies MSM

Here are the modes for this modem:

1225 – Default Mode. Available USB Mass Storage Device with CD-ROM and card reader. Corresponds to AT+ZCDRUN=9+AT+ZCDRUN=F

1403 – Operating Mode. Available RNDIS adapter and Mass Storage Device. Corresponds to AT+ZCDRUN=8+AT+ZCDRUN=F

1405 – CDC Ethernet Mode (the one we need). A mode similar to that described above (1403). Included in Linux after starting usb_modeswitch c default settings.

0016 – Download Mode. Under the name of ZTE., but simply a mode where available diagnostic port and two command (analog modem port and PC UI devices Huawei). Corresponds to AT+ZCDRUN=E

0076 – "real" Download Mode. Includes a standard for devices running QC methods.

If your modem does not appear as 19d2:1405 (or 1403), check USB 3G Modem#Mode switching article.

## Ethernet Connection Established

This modem is recognised as Ethernet interface. That means you don't need special programs to work with it.

Use NetworkManager or dhcdpc.

You will see that the LED (Blue - 2G/3G or Green - 4G) on modem is not blinking. To establish a connection, the following link (CGI command) should be entered in a browser:

http://192.168.0.1/goform/goform_set_cmd_process?goformId=CONNECT_NETWORK

To avoid entering this link every time, switch the modem to auto-connection mode:

http://192.168.0.1/goform/goform_set_cmd_process?goformId=SET_CONNECTION_MODE&ConnectionMode=auto_dial

If you are setting up internet using console (and therefore you have no browser), you should make request with referer, example:

    curl --header "Referer: http://192.168.0.1/index.html" http://192.168.0.1/goform/goform_set_cmd_process?goformId=CONNECT_NETWORK

otherwise you'll get response {"result":"faulure"}

## Commands

CGI command for 2G/3G/4G mode selection:

    http://192.168.0.1/goform/goform_set_cmd_process?goformId=SET_BEARER_PREFERENCE&BearerPreference=

following options available after "=" sign (case-sensetive)

    NETWORK_auto
    WCDMA_preferred
    GSM_preferred
    Only_GSM
    Only_WCDMA
    Only_LTE
    WCDMA_AND_GSM
    WCDMA_AND_LTE
    GSM_AND_LTE

This should be followed by the NETWORK CONNECT CGI command given before.

To switch the modem to FACTORY mode (WARNING! Unable to recieve further CGI commands, connection will be lost!), issue this link:

    http://192.168.0.1/goform/goform_process?goformId=MODE_SWITCH&switchCmd=FACTORY

After switching to FACTORY mode you can issues commands via PuTTY:

    putty /dev/ttyUSB0
    AT+ZCDRUN=8 - switch to 1403 mode (RNDIS)
    AT+ZCDRUN=9 - switch to 1225 mode (default)
    AT+ZCDRUN=F - exit DOWNLOAD mode and switch to selected mode (RNDIS or default)

## Telnet Connection

The modem is available for telnet connection:

    telnet 192.168.0.1
    login: root
    password: zte9x15

As you can see, the modem has Linux system inside. You can even install some ARM-base packages (mc, nano...) or change something in Web-menu. Explore it carefully!

## Switch Mode in OSX

The factual accuracy of this article or section is disputed.

Reason: Unless you give every Arch user a free Apple device, the reference to OSX is useless (Discuss in Talk:ZTE MF 823 (Megafon M100-3) 4G Modem#)

For some reason this device can get stuck in mode 0016 and fails to switch to any other mode. I was unsuccessful in trying to switch modes using usb_modeswitch and sending AT commands to /dev/ttyUSB0 on various Linux systems. I successfully managed to change modes from 0016 to 1403 using Mac OSX. I was then able to use the dongle on Linux.

In mode 0016 on OSX you will see the follow interfaces:

    /dev/tty.ZTEUSBATPort_
    /dev/tty.ZTEUSBModem_
    /dev/tty.ZTEUSBDIAGPort_

You can switch modes to 1403 by sending AT commands to the USBModem_ port by doing:

    screen /dev/tty.ZTEUSBModem_ 9600

    >>ATI
    Manufacturer: ZTE CORPORATION
    Model: MF823
    Revision: MF823_T03
    IMEI: 866948013728723
    +GCAP: +CGSM

    >>AT+CREG?
    +CREG: 0,1
    OK

    >>AT+COPS?
    +COPS: 0,0,"Telstra Mobile",7
    OK

    >>AT+ZCDRUN=8+AT+ZCDRUN=F
    exit download mode result(0:FAIL 1:SUCCESS):1
    OK

Now the device should act as a ethernet interface no matter which system you plug it into.

## See also

ZTE MF823 Modem - Linux & Serial Diags

Gsmforum.ru - ZTE MF823 thread (in Russian), check #7 thread for unlock instructions

Category:

- Modems

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