3G dongle working (Micromax MMX 300G, Fastweb FW 721, Omega technology)

Hi all,
just wanted to share a working usb_modeswitch configuration on Lede 18.06.1 for an ancient 3G USB 7.2Mbps dongle/stick that still runs in ppp mode. This 3G USB stick can be found under at least two different names: Micromax MMX 300G (see here), and Fastweb Key Telsey FW 721 Black, type WKH7UBMU1 ver. 0FWB, as it was marketed back in 2009 by the Italian service provider Fastweb. Here and there it's said to be a Telsey device and lsusb reports it to be manufactured by Omega Technology.
Openwrt needs first of all to be properly configured to support legacy ppp over 3G connection on USB sticks. And when usbmode loads the default /etc/usb-mode.json this dongle is not recognized, not switched properly and ppp fails.

Below you can find a working usbmode configuration file in json format you can pass directly with something like usbmode -c custom_conf.json.
For this dongle to work, a working custom_conf.json can be:

{
	"messages" : [
		"55534243123456788000000080000606f50402527000000000000000000000",
],
"devices" : {
		"1c9e:f000": {
                        "*": {
                                "t_vendor": 7326,
                                "t_product": [ 36864, 38403, 38405, 38407, 39168 ],
                                "msg": [ 0 ],
                                "wait": 0
                        },
                },
	}
}

or, if you want to integrate the configuration with the default /etc/usb-mode.json you have to find the 1c9e:f000 stanza and modify it as follows (the default contains other lines that mess with this device):

"1c9e:f000": {
                        "*": {
                                "t_vendor": 7326,
                                "t_product": [ 36864, 38403, 38405, 38407, 39168 ],
                                "msg": [ 17 ],
                                "wait": 0
                        }
                },

if everything goes fine, lsusb gives the following:

root@router:~# lsusb
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 005: ID 1c9e:9603 OMEGA TECHNOLOGY 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

and three TTY devices are created under /dev/ttyUSB0-1-2, being /dev/ttyUSB2 the one to be referenced to in /etc/config/network when configuring the 3G wan interface.

hope this helps - this dongle is old and slow (7.2Mbps), but might still be viable for an emergency 3G wan uplink.

2 Likes

Thank you. I actually tried to set up the modem two years ago but failed. But I also found out the correct message from my Linux device's usb_modeswitch log. PFA the log screenshot. No help was available on the forum. After 2 years, today, I again searched the forum and there were actually 3 posts. This, your post, and this.

Last time I failed because I didn't reboot the device. usbmode -s -v -c usb-mode-custom.json always returned Failed to send switch message. This time, I deleted the contents of the default config file and replaced it with the custom JSON. Rebooted and it worked like a charm. :innocent: