Communication through GSM Data and GPRS

GPRS - General Packet Radio Service

With GPRS the VTU008 is connected all the time and positions are sent at pre-set intervals. Each position is 36 bytes only, but a 'header' must be also sent, which doubles the size of data being transmitted. Even though some operators charge for the header, the size of data sent is still very small. The internal algorithm makes sure that data is sent only when your vehicle moves by a set distance, time and angle keeping costs very reasonable - with default settings travelling 1,000 miles per month you can expect to transmit approximately 1MB of data. Cost per MB varies from operator to operator, from £1 to £8 on PAYG cards. Currently Orange offers a 'bolt-on' on their PAYG SIM card £4 per month for 4MB - this would be enough to send positions very frequently. If you are using a PAYG SIM card, you will need to make sure that it is charged, otherwise the unit will not be able to transmit. It will, however, store positions in the internal memory (up to 250,000 positions can be stored) and will transmit them as soon as you add credit.

Data is sent to our web server, where it waits for you to download it through your broadband connection using the Navigator tracking software. Navigator includes street level maps of Great Britain, other western European countries are optional. Downloads can be scheduled at pre-set intervals.

GSM data

For this connection you will need a dial-up modem, either standard, or GSM. The tracking unit keeps storing your positions internally (up to 250,000 can be stored). These can be retrieved at any time by dialling directly into the unit from your PC. The internal algorithm makes sure that positions are saved only when you move by a set distance and time, so that you do not need to download unnecessary data. With the supplied Navigator tracking software you can execute three basic functions - locate, track and download history. Both locate and track will return live (current) position(s).

Your SIM card must be 'data' enabled, which is not default, but easily obtainable free of charge from most operators. To our knowledge only Vodafone provides this service on PAYG SIM cards. As the SIM card only receives calls (if you do not use available alarm features), there is no need to charge the card and the transmission time will be on your BT bill ( if you use BT) just like if you call a mobile phone.

On average it takes about 2 minutes to download one weeks history (depending on your settings, distance travelled and travelling time) and should be below £2 per month.


If you need to see positions of your vehicle/asset frequently, then you will need to use GPRS features, but if you just want to know where your vehicle/asset has been, then GSM data is more suitable.

In general GSM data is less suitable for keeping track of fleets of vehicles because you must dial each one in turn.

As the VTU008 is compatible with both systems, you can switch between these two systems at any time - the tracking unit can be set remotely through GSM data connection or using an optional serial cable.