Thursday, July 21, 2011

Travels with Mobile Broadband

We're on travel in the UK aboard a boat in St. Katherine's Dock, London. There are some 33 different WiFi access points, the stronger two being and But even these have spotty connectivity. So we sought a different solution. This relates our trials (and success) in employing "Mobile Broadband" solutions.

One alternative to WiFi is to use 3G Mobile Broadband "dongles" offered by BT, Vodafone, ThreeNet, and others. We chose Vodafone, which currently (July 2011) offers the ZTE K3570-Z "dongle".

These dongles are essentially a cellphone on a USB stick. They appear as a CD ISO containing Mac and Windows software but then are "Modeswitched" to appear as serial modems. This is all bleeding edge technology: easy if you know how but frustratingly difficult to figure out how if you don't. It took us about a week of experimentation and googling to finally crack it.

Part of the problem is the "can't get there from here" problem: You need to download software to install to have the thing work, but if you can't get it to work you can't connect to download! The WiFi connections have a very short timeout, the native Windows apps are huge (88MB). So finding an amazingly simple solution is amazingly difficult to do. But we did and here is how.

First, do your homework. We went around Robin Hood's barn but by then had learned enough to be able to responsibly get an appointment with a Vodafone technician at one of the stores. The first thing he did was transfer the 88 MB software and set it up on Windows (We're running Windows XP on VirtualBox). But then two hours elapsed while he fiddled with APNs, PINs, passwords, and other things, none of which worked. So as it was time for lunch I thanked him for his time and for the software and left.

When I got home the first thing I discovered was that he had created a second modem. I deleted it and off we went - but on Windows. Still no joy on Linux.

There is a site ( that offers a bunch of Linux programs under a Vodafone logo but they are for the older Huawei modems and don't seem to work with my unit.

But finally I found

They have two programs: one with and one without the usb-modeswitching software. The latter uses the modeswitch software installed on your system, the former provides its own.
  • Full version embeds latest Usb-ModeSwitch version along with its device database. You should choose it if your distribution does not provide a recent Usb-ModeSwitch version, and you intend using a switchable USB modem.
  • Binary free version is architecture independent but it requires Usb-ModeSwitch being installed on your system.
I first installed Sakis3G binary free. It connected to "Interface #3" but no packets were exchanged and ping did not respond from the gateway.

So I deleted that and tried the full version.

Still no joy. It connected to the network but no communications occurred. Checked the firewall, no problem...

But then I realized that knetworkmanager was still running. Shut it down, tried again, success!

Woohoo! Finally!

There are some tricks picked up in the earlier travels (travails?):

  • Run the command as root. Getting the root password doesn't seem to work on my system.
  • Get the correct APN. Sakis3G helpfully lists the various options for vodafone. In my case it is the "new" PAYG APN: ppbundle.internet
  • Get the PIN and PUK codes printed on the back of the SIM card card before you throw away the residue! If you fail in this regard (throw away the residue before recording the PIN and PUK) you can read the phone number off the SIM then use the Vodafone site to request the PIN and PUK(assuming you can get some connectivity to reequest them). The PIN is 0000 by default.
  • Get the correct phone number to dial. In my case it was *99***6#. The dongles have a number of different "connection profiles" (sets of Internet settings) that vary with manufacturer and service. Here the 6 refers to the sixth connection profile.
  • Consensus of my research is that /dev/ttyUSB3 is the only one, of the five serial ports generated, that responds. Presumably this is the only one that corresponds to a modem interface on the ZTE K3570-Z.
  • Make sure you have changed the network to NOT use a network manager. Under openSUSE 11.4 this is accomplished with yast2 network > Network card > Global Options > Traditional Method with ifup. You don't actually have to use ifup since Sakis3G does that for you, but you have to do this to allow it to do it for you.

If you want to learn more about serial ports and modems then Sakis has a comprehensive tutorial at

So other than that, Mrs. Lincoln...

Easy when you know how.

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