Connect to internet Huawei E3531

Your device is rather new and not directly supported by your version of Ubuntu yet.
But there is something to try:

- Open the Terminal (if in doubt press Ctrl+Alt+T) and copy in this line:
sudo usb_modeswitch -W -I -v 12d1 -p 15e7 -M 55534243123456780000000000000011062000000101000100000000000000
- Press enter, enter your password (nothing will be shown, not even ***) and press enter again.
- Copy the output for us.
- Do the same for the line:
lsusb

With the output we are able to assist you.

luis@luis-G41M-Combo:~$ sudo usb_modeswitch -W -I -v 12d1 -p 15e7 -M 55534243123456780000000000000011062000000101000100000000000000
[sudo] password for luis:
Taking all parameters from the command line

 * usb_modeswitch: handle USB devices with multiple modes
 * Version 1.2.3 (C) Josua Dietze 2012
 * Based on libusb0 (0.1.12 and above)

 ! PLEASE REPORT NEW CONFIGURATIONS !

DefaultVendor= 0x12d1
DefaultProduct= 0x15e7
TargetVendor= not set
TargetProduct= not set
TargetClass= not set
TargetProductList=""

DetachStorageOnly=0
HuaweiMode=0
SierraMode=0
SonyMode=0
QisdaMode=0
GCTMode=0
KobilMode=0
SequansMode=0
MobileActionMode=0
CiscoMode=0
MessageEndpoint= not set
MessageContent="55534243123456780000000000000011062000000101000100000000000000"
NeedResponse=0
ResponseEndpoint= not set

InquireDevice disabled
Success check disabled
System integration mode disabled

usb_set_debug: Setting debugging level to 15 (on)
usb_os_find_busses: Found 005
usb_os_find_busses: Found 004
usb_os_find_busses: Found 003
usb_os_find_busses: Found 002
usb_os_find_busses: Found 001
usb_os_find_devices: Found 002 on 005
skipped 1 class/vendor specific interface descriptors
skipped 1 class/vendor specific interface descriptors
usb_os_find_devices: Found 001 on 005
error obtaining child information: Inappropriate ioctl for device
usb_os_find_devices: Found 001 on 004
usb_os_find_devices: Found 003 on 003
skipped 1 class/vendor specific interface descriptors
usb_os_find_devices: Found 001 on 003
error obtaining child information: Inappropriate ioctl for device
usb_os_find_devices: Found 001 on 002
usb_os_find_devices: Found 006 on 001
usb_os_find_devices: Found 003 on 001
skipping descriptor 0xB
skipped 1 class/vendor specific endpoint descriptors
skipped 5 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
skipped 25 class/vendor specific interface descriptors
skipping descriptor 0xB
skipped 1 class/vendor specific endpoint descriptors
skipped 4 class/vendor specific interface descriptors
skipped 2 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
skipped 2 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
usb_os_find_devices: Found 001 on 001
error obtaining child information: Inappropriate ioctl for device
error obtaining child information: Inappropriate ioctl for device
Looking for default devices ...
  searching devices, found USB ID 04d9:1503
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 046d:c05f
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 12d1:15ca
   found matching vendor ID
  searching devices, found USB ID 046d:082b
  searching devices, found USB ID 1d6b:0002
 No devices in default mode found. Nothing to do. Bye.

luis@luis-G41M-Combo:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 046d:082b Logitech, Inc.
Bus 003 Device 003: ID 046d:c05f Logitech, Inc.
Bus 005 Device 002: ID 04d9:1503 Holtek Semiconductor, Inc. Shortboard Lefty
Bus 001 Device 006: ID 12d1:15ca Huawei Technologies Co., Ltd.
luis@luis-G41M-Combo:~$

Your lsusb output shows a product ID different from what Thomas Krueger seems to have expected (yours seems to be the ID of Huawei E3131!), please try again and provide the output of the following three commands:

lsusb
sudo usb_modeswitch -W -I -v 12d1 -p 15ca -M 55534243123456780000000000000011062000000101000100000000000000
lsusb

luis@luis-G41M-Combo:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 046d:082b Logitech, Inc.
Bus 003 Device 002: ID 046d:c05f Logitech, Inc.
Bus 005 Device 002: ID 04d9:1503 Holtek Semiconductor, Inc. Shortboard Lefty
Bus 001 Device 005: ID 12d1:15ca Huawei Technologies Co., Ltd.
luis@luis-G41M-Combo:~$ sudo usb_modeswitch -W -I -v 12d1 -p 15ca -M 55534243123456780000000000000011062000000101000100000000000000
[sudo] password for luis:
Taking all parameters from the command line

 * usb_modeswitch: handle USB devices with multiple modes
 * Version 1.2.3 (C) Josua Dietze 2012
 * Based on libusb0 (0.1.12 and above)

 ! PLEASE REPORT NEW CONFIGURATIONS !

DefaultVendor= 0x12d1
DefaultProduct= 0x15ca
TargetVendor= not set
TargetProduct= not set
TargetClass= not set
TargetProductList=""

DetachStorageOnly=0
HuaweiMode=0
SierraMode=0
SonyMode=0
QisdaMode=0
GCTMode=0
KobilMode=0
SequansMode=0
MobileActionMode=0
CiscoMode=0
MessageEndpoint= not set
MessageContent="55534243123456780000000000000011062000000101000100000000000000"
NeedResponse=0
ResponseEndpoint= not set

InquireDevice disabled
Success check disabled
System integration mode disabled

usb_set_debug: Setting debugging level to 15 (on)
usb_os_find_busses: Found 005
usb_os_find_busses: Found 004
usb_os_find_busses: Found 003
usb_os_find_busses: Found 002
usb_os_find_busses: Found 001
usb_os_find_devices: Found 002 on 005
skipped 1 class/vendor specific interface descriptors
skipped 1 class/vendor specific interface descriptors
usb_os_find_devices: Found 001 on 005
error obtaining child information: Inappropriate ioctl for device
usb_os_find_devices: Found 001 on 004
usb_os_find_devices: Found 002 on 003
skipped 1 class/vendor specific interface descriptors
usb_os_find_devices: Found 001 on 003
error obtaining child information: Inappropriate ioctl for device
usb_os_find_devices: Found 001 on 002
usb_os_find_devices: Found 005 on 001
usb_os_find_devices: Found 003 on 001
skipping descriptor 0xB
skipped 1 class/vendor specific endpoint descriptors
skipped 5 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
skipped 25 class/vendor specific interface descriptors
skipping descriptor 0xB
skipped 1 class/vendor specific endpoint descriptors
skipped 4 class/vendor specific interface descriptors
skipped 2 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
skipped 2 class/vendor specific interface descriptors
skipping descriptor 0x25
skipped 1 class/vendor specific endpoint descriptors
usb_os_find_devices: Found 001 on 001
error obtaining child information: Inappropriate ioctl for device
error obtaining child information: Inappropriate ioctl for device
Looking for default devices ...
  searching devices, found USB ID 04d9:1503
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 046d:c05f
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 1d6b:0001
  searching devices, found USB ID 12d1:15ca
   found matching vendor ID
   found matching product ID
   adding device
  searching devices, found USB ID 046d:082b
  searching devices, found USB ID 1d6b:0002
 Found device in default mode, class or configuration (1)
Accessing device 005 on bus 001 ...
Getting the current device configuration ...
 OK, got current device configuration (1)
Using first interface: 0x00
Using endpoints 0x01 (out) and 0x81 (in)

USB description data (for identification)
-------------------------
Manufacturer: HUAWEI
     Product: HUAWEI Mobile
  Serial No.: FFFFFFFFFFFFFFFF
-------------------------
Looking for active driver ...
 OK, driver found ("usb-storage")
 OK, driver "usb-storage" detached
Setting up communication with interface 0
Using endpoint 0x01 for message sending ...
Trying to send message 1 to endpoint 0x01 ...
 OK, message successfully sent
Resetting response endpoint 0x81
Resetting message endpoint 0x01
USB error: could not release intf 0: No such device
 Device is gone, skipping any further commands
-> Run lsusb to note any changes. Bye.

luis@luis-G41M-Combo:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 046d:082b Logitech, Inc.
Bus 003 Device 002: ID 046d:c05f Logitech, Inc.
Bus 005 Device 002: ID 04d9:1503 Holtek Semiconductor, Inc. Shortboard Lefty
Bus 001 Device 006: ID 12d1:1506 Huawei Technologies Co., Ltd. E398 LTE/UMTS/GSM Modem/Networkcard
luis@luis-G41M-Combo:~$

http://wiki.gentoo.org/wiki/Huawei_E367

Or

http://bytefish.de/blog/huawei_e352s5/

You don't need to install usb-modeswitch as it is in a default install.

As you can see from the lsusb output before and after the usb_modeswitch command, the device was successfully initialized as modem, and should now work. You should now see an active choice "WLAN" in the network management applet. (Note that the device has to be re-initialized after each reboot or replugging.)

What still has to be done is automatic the initialization with help of the usb_modeswitch tools. Your device seems to be too new to be already contained in the data, so you have to modify the data and add an entry for "vendor 12d1 product 15ca" similar to most of the other Huawei (vendor 12d1) products.

What is the output of the commands
sudo updatedb
locate 12d1

luis@luis-G41M-Combo:~$ sudo updatedb
[sudo] password for luis:
luis@luis-G41M-Combo:~$ locate 12d1
/home/luis/.compiz-1/session/10326b5c163dc3d12d136369479149366200000013700038
luis@luis-G41M-Combo:~$

sudo updatedb dint gave any result.

Ok. It seems that the usb_modeswitch package for utopic already contains everything what you need, but that version is not provided in the repositories fro precise.
I assume it is much easier to install the utopic packages on your precise system (I guess that should work without problems), than trying to manually add the required information about your device into your current system.

Please provide the output of the following commands:

uname -a
lsb_release -a
apt-cache policy usb-modeswitch usb-modeswitch-data

luis@luis-G41M-Combo:~$ uname -a
Linux luis-G41M-Combo 3.2.0-70-generic-pae #105-Ubuntu SMP Wed Sep 24 20:08:22 UTC 2014 i686 i686 i386 GNU/Linux
luis@luis-G41M-Combo:~$ lsb_release -a
LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch
Distributor ID: Ubuntu
Description: Ubuntu 12.04.5 LTS
Release: 12.04
Codename: precise
luis@luis-G41M-Combo:~$ apt-cache policy usb-modeswitch usb-modeswitch-data
usb-modeswitch:
  Installed: 1.2.3+repack0-1ubuntu2
  Candidate: 1.2.3+repack0-1ubuntu2
  Version table:
 *** 1.2.3+repack0-1ubuntu2 0
        500 http://za.archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        500 http://archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status
usb-modeswitch-data:
  Installed: 20120120-0ubuntu1
  Candidate: 20120120-0ubuntu1
  Version table:
 *** 20120120-0ubuntu1 0
        500 http://za.archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        500 http://archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status
luis@luis-G41M-Combo:~$

Open a terminal window and issue the following commands

cd ~/Downloads
wget http://za.archive.ubuntu.com/ubuntu/pool/main/u/usb-modeswitch/usb-modeswitch_2.2.0+repack0-2ubuntu1_i386.deb
wget http://za.archive.ubuntu.com/ubuntu/pool/main/u/usb-modeswitch-data/usb-modeswitch-data_20140529-1_all.deb
sudo dpkg -i usb-modeswitch_2.2.0+repack0-2ubuntu1_i386.deb usb-modeswitch-data_20140529-1_all.deb

Then reboot, wait half a minute, plug in your WLAN stick, wait another half minute, and look into the network management applet whether you see an option to configure and use WLAN.

If there is any error message or problem, please copy/paste the output that you receive.

Great it worked, difficult but accomplished.
Thank you

Thanks Manfred Hampl, that solved my question.