# 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. USB Mass Storage Device + CD-ROM + card reader.

1403 - Modem mode. RNDIS + Mass Storage Device.

1405 - CDC ethernet mode - the one we need

0016 - Download mode

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

## Connection

This modem is recognized 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 estabilish 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

## 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!

## External links

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

Category:

- Modems