Reliance ZTE AC2738 USB modem on Debian Wheezy

Recently my old Reliance NetConnect+ USB modem stopped working because of hardware issue. The old one is made by HUAWEI and worked out of the box on Debian Wheezy. The new one that I bought as a replacement is ZTE model AC2738 and refused to work out of the box. I did the following to make it work.

Created new file /etc/udev/rules.d/90-zte.rules and added the following.

SUBSYSTEM=="block", SUBSYSTEMS=="scsi", ATTRS{model}=="USB Storage FFE9", ACTION=="add", RUN+="/sbin/modprobe usbserial vendor=0x19d2 product=0xffe9"

How did I arrive at that solution?

There is no readily available driver for this modem in linux. So, when this device is plugged in, usb-storage module is loaded by default. Since usbserial kernel module is compatible with most of the USB modems, I tried loading this manually using following command.

/sbin/modprobe usbserial vendor=0x19d2 product=0xffe9

Vendor and Product id can be obtained using the lsmod command. The above command successfully recognized the modem and I was able to use wvdialconf to detect the modem.

The next step is to automate this so that this is loaded every time machine boots. For this I added a udev rule that I mentioned above. In order to figure out which unique match keys is to be used, the following command helped.

udevadm info --name=/dev/sdb --attribute-walk

The device name may change with respect to your system. I used dmesg command to figure that out.

The fun part is that, the effort that I put up for figuring this out was useful for another member of ILUGC. The entire discussion thread is here.