Review by Lutz Bendlin
 After our review of the WorldTracker Data Logger we are now having a closer look at the WorldTracker SMS. Special thanks to Gilbert Walz of Security Concepts for making this possible. As I said in the first review those devices are slightly outside of our "Mobile Navigation" comfort zone, and are not something you come across every day.
The size of the two devices is nearly identical, and they may be used by the same people (we are talking covert operations here) but their functionality is very different.
The Data Logger is working quietly and is recording the target's position at a given interval. The recorded data can only be retrieved and analysed once the receiver is recovered from the tracked vehicle.
The World Tracker SMS on the other hand has two communication channels - a GPS receiver to determine the position of the "target" and a GSM phone interface to "phone home" - to receive orders and setup instructions, and to report the GPS position back to the tracking, uhm, persons. The WorldTracker SMS has no other interface - neither serial nor BlueTooth ports are available. If you want to know the position you need to call - that's how easy it is.
What's in the box?
 The World Tracker SMS is accompanied by
- a second battery,
- a mains charger,
- a car charger with very long connecting cable,
- a magnetic battery box,
- the same fancy suction-cup-soap-box holder like for the Data Logger.
As you can guess from these accessories the WorldTracker SMS is expected to be (semi)permanently installed in the car that should be tracked. Preferably hard wired into the car's power system, yet somewhere where the receiver has a chance to pick up a reliable GPS signal. The receiver uses a state of the art SiRF III chipset which obviously helps a lot to get a fix and hold on to it.
If you run the receiver on batteries you have about 24 hrs with the standard battery, and about four days with the additional quad AA battery pack (the one with the round magnet).
At first I was not sure what the spare battery is for but then I understood that the device actually has two functions. It can be used for covert tracking (without the target knowing about it) but also for consented tracking when the tracked person actually has an interest in being locateable. And for that scenario a second battery may come in handy.
A quick walk around the receiver
 
On the top left is the Link LED - it will blink red when no GSM network can be found and will stay on when the receiver is booked into a GSM network. On the top right is the GPS fix LEX which will light up steady when the receiver has a position fix.
On the side is the on/off switch (a physical switch that is way too easy to engage) and the GSM SIM card slot with a little Eject button. Any SIM will do as long as it supports sending and receiving SMS messages. More on that later.
On the bottom left is the "Park" button, together with a little green LED that's pretty tough to see. You press this button when you leave your car and want the WorldTracker SMS to call you when your car gets moved by someone else (read: when someone is borrowing it without asking). The only tricky thing here is to remember to press the button again when you come back...
The "Panic" button will trigger the audible alarm - which I found hilarious since it is barely hearable - as well as a sequence of SOS SMS messages.
The device has a lanyard at the bottom where you can attach neck straps etc. There you also find the power socket (weird format, not the standard iPAQ size) and a micro USB com port that is "reserved for special cases" according to the manual. At the very bottom you see the slider for the battery compartment. Its construction left me doubting as to the watertightness of the device. It will stand some splashing but certainly no immersion in water.
So how does it work?
To get started you need to have a valid SIM card, and need to know its phone number. You can either use one of your own SIM cards or you buy a SIM from Security Concepts as part of the package.
That's it, you are in business. Now call the number of the SIM, and - provided the receiver has a fix - it will reply with a SMS that basically contains a $GPRMC line from the standard NMEA stream, including the position and the speed.
If the receiver doesn't have a fix yet it will let you know too.
Now did you notice something? We did not need to tell the receiver who we are! Whenever the WorldTracker SMS receives a call with a valid caller ID it will dutifully report the current GPS position back to that phone number.
I think this is a problem. I receive calls pretty regularly where people mistype the number and actually wanted to call someone else. Imagine their surprise when they call the receiver by accident, and then receive a SMS with some cryptic text... Even worse if these people recognize that as a GPS position...
I do hope that future versions of the WorldTracker implement a "whitelist" of numbers that are authorized to call in.
Next you can send the setup parameters to the receiver - via SMS. This is actually the most tricky part, and it does take some learning (and wasting of SMS) to get it right.
The first message tells the unit this is the list of phone numbers to call (the "2", followed by up to five numbers). 32075 is actually a valid phone number, and represents the SMS Gateway at Security Concepts - more on that later.
If you don't get the format right you get a pretty unhelpful error message:
I found it particularly difficult to change the username and password for the device, and finally gave up on that. It also didn't seem to have any impact on the functionality.
Although you can specify up to five phone numbers only the first one is actually used for the standard automatic position reporting, so you will have to decide if you want web tracking (via the SMS Gateway) or if you want to just receive a bunch of SMS in your normal phone inbox.
You can specify the interval in minutes between SMS, and this can be anything between 1 and 120 minutes. This example above shows that I told the receiver to send a SMS every 60 minutes, and do it 99 times.
If the setup was successful you will soon start receiving the automatic position messages. Unfortunately there is no way to tell how many messages you still have left , so you need to keep track of that yourself (It's also a problem if more than one person is programming the same receiver. Since the feedback from the receiver is most unhelpful you have no way of telling what it's true status is. You may have set the reporting to once every 60 minutes but the other person may set it to once every minute, or disable reporting completely).
The receiver will tell you if the GPS position is current ("Now") or if the last valid GPS signal was x minutes ago. That's an interesting feature. If the car gets parked somewhere without GPS reception chances are pretty good that the GSM network does still work, so the receiver can at least send you the last known position.
You can setup a number of other features, most notably the "park/towed" feature. If the car is moving out of a radius of 300 metres and you have the Park function enabled (either via the button, or via a SMS command) then you will receive SMS notification that your car is not where it should be.
If you hit the Panic button the receiver will bleep miserably (I really expected a 110 dB sound) and send out a slew of "SOS" SMS to all the registered phone numbers and will continue to do so for 20 times every two minutes.
That's about it - the only feature we did not yet cover is the web tracking. Assuming you have set the first phone number to the SMS Gateway at Security Concepts you can actually see all the sent SMS on a map. That's a pretty cool feature, particularly when you need to track multiple devices. You just have to be aware that your messages are processed by a third party - that may not be what you intended. And yes, this website uses Google Maps technology.
I had set the SMS interval to once every hour (to keep my phone bill down) so the path display is a bit choppy. If you have a flat rate SMS plan you can certainly reduce the interval, down to once every minute.
The website also keeps the historic data (note the calendar on the bottom) so you can lookup the tracking details for previous days too.
There's also a csv (comma separated values) export feature and a KML link - this will allow you to see the track in Google Earth. Unfortunately the Google Earth file only has the last active day's data.
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