USB 3G Modem
A number of mobile telephone networks around the world offer mobile internet connections over UMTS (or EDGE or GSM) using a portable USB modem device.
- 1 Remove the PIN
- 2 Device identification
- 3 Mode switching
- 4 Connection
- 5 Reading SMS
- 6 Fix image quality
Remove the PIN
First of all use your SIM card in a normal phone and disable the PIN request if present. If the SIM card asks the PIN wvdial will not work.
Failing that, you can also use mmcli to unlock the SIM card:
# mmcli -i SIMNUMBER --pin=XXXX
where SIMNUMBER can be found using
mmcli -L and
mmcli -m X.
Examine the output of
which will show the vendor and product IDs of the device. Note that some devices will show two different product IDs at different times as explained below.
Often these devices will have two modes (1) USB flash memory storage (2) USB Modem. The first mode, sometimes known as ZeroCD, is often used to deliver an internet communications program for another operating system and is generally of no interest to Linux users. Additionally some have a slot into which the user can insert an additional flash memory card.
A useful utility for switching these devices into modem mode is official repositories., available in the
Udev rules are supplied with the package in
/lib/udev/rules.d/40-usb_modeswitch.rules. This contains entries for many devices, which it will switch to modem mode upon insertion.
When a device is switched, its product ID may change to a different value. The vendor ID will remain unchanged. This can be seen in the output of
Some devices are supported in the USB serial kernel module called "option" (after the Option devices, but not limited to just those) and may be used without usb_modeswitch.
Udev itself included a utility called
/lib/udev/modem-modeswitch. In udev 157 this was renamed to
/lib/udev/mobile-action-modeswitch and morphed into a tool that only switches Mobile Action cables. For other devices use
After installing NetworkManager.and , you just need to install to make the modem work with
Make sure both NetworkManager and ModemManager services are running, see systemd#Using units for details.
Make sureand are installed.
A system restart might be necessary for ModemManager to detect the USB modem. After you restart the NetworkManager-applet and plug the modem in again NetworkManager should recognize the modem in the menu without further configuration. Setting up the modem in NetworkManager is self-explanatory, you should only need the login-information provided by your network provider.
In case NetworkManager does not recognize the modem, check the output of ModemManager.service:
# systemctl status ModemManager
If you get error messages such as "Couldn't check support for device" and "not supported by any plugin", you may have to whitelist your device using the ModemManager filter rules https://www.freedesktop.org/software/ModemManager/api/1.8.0/ref-overview-modem-filter.html
Whilst running ModemManager gammu will not work. SMS and Ussd codes can be still used with.
pppd can be used to configure 3g connections. Step by step instruction is available on 3G and GPRS modems with pppd. Optionally, AUR can be used to simplify the pppd configuration using dialog interface.
See main article: wvdial
Netctl can be used to establish a connection using a USB modem. An example configuration file provided by
/etc/netctl/examples/mobile_ppp. Minimally you will probably have to specify
Interface=cdc-wdmX Connection=mobile_ppp PhoneNumber=XxxxXXXX AccessPointName=Broadband
libmbim from the official repositories. To bring up the modem you can use
mbim-network which is a wrapper for
mmcli calls. First create a profile for mbim-network.
APN=BroadbandNow connect to the network with
# mbim-network /dev/cdc-wdmX start. Then bring up the interface and get an ip address:
# ip link set wwanY up # dhcpcd wwanY
Low connection speed
Someone claims that the connection speed under Linux is lower than Windows: 
A short summary for possible solutions which are not fully verified. In most of conditions, the low speed is caused by bad receiver signals and too many people in cell. But you still could use the following method to try to improve the connection speed.
AT+CGEQREQ commands can be used to set the QoS. It is also possible to decrease and limit the connect speed.
Add the following
Init command in
Init6 = AT+CGEQMIN=1,4,64,640,64,640 Init7 = AT+CGEQREQ=1,4,64,640,64,640
Baud parameter in wvdial.conf could be used to increase the connection speed.
Baud = 460800
But the official Huawei E261 windows application set the Baud=9600 under Windows Vista. More verifications are needed to double check this point.
Monitor used bandwith
Frequently a 3G connection obtained via a mobile phone operator comes with restricted bandwidth, so that you are only allowed to use a certain bandwidth per time (e.g. 1GB per month). While it is quite straight-forward to know which type of network applications are pretty bandwidth extensive (e.g. video streaming, gaming, torrent, etc.), it may be difficult to keep an overview about overall consumed bandwidth.
Connection halts after few minutes running
This problem occurs on some modems which locked by a mobile operator. You can successfully connect to the internet but after few minutes connection halts and your modem reboots. That happens because an operator built a some checks into modem firmware so a modem checks if a branded software is running on your pc, but usually that software is Windows-only, and obviously you don't use it. Fix (it works on ZTE-mf190 at least) is simple - send this command through serial port (use minicom or similar soft):
This command will delete a NODOWNLOAD.FLG file in the modem's filesystem - it will disable such checks.
This was tested on a Huawei EM770W (GTM382E) 3g card integrated into an Acer Aspire AS3810TG laptop.
$ pacman -S gnokii $ mkdir -p $XDG_CONFIG_HOME/gnokii
Usually the configuration directory is
$ cp /etc/gnokiirc ~/.config/gnokii/config
~/.config/gnokii/config as follows:
port = /dev/ttyUSB0
You may have to use a different port depending on your configuration, for example
/dev/ttyUSB1 or something else:
model = AT connection = serial
You need to be part of the
uucp group to use
/dev/ttyUSB0, for example if your user is called "x":
# gpasswd -a x uucp $ newgrp uucp
The newgrp command allows you to take advantage of the new group assignment immediately without having to logout/login.
Then launch gnokii:
Click on the "SMS" icon button, a window opens up. Then click: "messages->activate sms reading". Your messages will show up in the window.
command line script
A small command line script using gnokii to read SMS on your SIM card (not phone memory) without having to start a GUI:
$ gnokii --getsms SM 0 end 2>&1|grep Text -A1 -B3|grep -v Text
What it does:
gnokii # invoke gnokii --getsms SM 0 end # read SMS from SM-memory location (=SIM card) starting at 0 and reading all occupied memory locations ("end") 2>&1 # connect STDERR to STDOUT to make sure the output from the --getsms command can be piped to grep |grep Text # pipe output from gnokii to grep, anchoring at output containing "Text" -A1 -B3 # print one line after the matched pattern and three lines before the matched pattern |grep -v Text # grep result to another grep to exclude the "Text" line (-v for inverting the pattern)
Granted this does not work very well if your SMS contains the word "Text", but you may adapt the script to your liking.
Fix image quality
If you are getting low quality images while browsing the web over a mobile broadband connection with the hints "shift+r improves the quality of this image" and "shift+a improves the quality of all images on this page", follow these instructions:
Edit /etc/tinyproxy/tinyproxy.conf and insert the following two lines:
AddHeader "Pragma" "No-Cache" AddHeader "Cache-Control" "No-Cache"
systemctl start tinyproxy
Configure your browser to use localhost:8888 as a proxy server and you are all done. This is especially useful if you are using, for example, Google Chrome which, unlike Firefox, does not allow you to modify the Pragma and Cache-Control headers.