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TK Device - How to use GPRS

Most TK type devices can send their position information using one of two methods:

SMS – In this mode the TK device receives commands and sends all its responses via SMS usually directly to the phone that sent the request.

GPRS - In this mode commands are still normally (although some devices can be controlled via GPRS too) sent to the TK device via SMS from a phone.  However, position & alarm updates are sent not to the phone but directly to a configured server.   It is then the job of the program running on the server to accept and process these position messages.  In most cases you would then need to log into a service with a browser in order to see the actual position on a map.

Why do I need a GPS Mapping Service?

Under normal circumstances you cannot directly communicate with a TK device from your Android phone using GPRS. This is basically because the TK device can only speak to a fixed IP address and port.  The IP address that you have on your phone is normally provided (very) dynamically by your cellular carrier and may (will) change depending upon your location, network congestion etc.  Whilst you can find out what IP address you are currently assigned you cannot rely on it being the same a few seconds later.

To use GPRS mode you basically have to go through an intermediate server/service which has a fixed IP address (which they provide to you when you sign up).  The server must be running some software that can accept connections from the TK device and read and process the incoming position messages.  The service provider then normally makes this information available via a web page which you access with a browser on your PC or phone.

There are several web based services available that will allow you to connect to their servers so that you can use GPRS mode. Some of these are free – some charge. A reasonably well known one is at http://gps-trace.com (please note I have no connection with this service and there may be

many others that may suit you better) A good place for further general information is the http://www.gpspassion.com website they have a lot of excellent information and a forum that deals with TK devices. (Again, I have no connection with them and other forums are available)

Configuring GPRS.

You will need to set the following in order to use GPRS.

  1. Your TK SIM must be enabled for GPRS and have some credit on it.
  2. The Access Point Name (APN) for the TK device’s cellular carrier.
  3. An APN userID and/or password if required. Some carriers require them, some don’t. You may be able to find this information on your carrier’s web page or you may need to contact them directly.
  4. Host server IP and port address. These will be supplied by whichever GPS Mapping Service you choose to use.

Will I ever be able to use GPRS directly with TKMon

I am working on a linked service for TKMon which will allow you to use GPRS directly (via my servers) from the app.  Unfortunately this will not be free (estimate cost to be approximately £1/500msgs/month) as I have to support a server infrastructure.  It will however be completely transparent to the user and will look just like the SMS functionality.  i.e. no need to use a browser and messages will be stored and displayed like the SMS ones but without the SMS costs.  (Depending upon the type of usage you need and your cellular tariff this can be a much cheaper option than using

SMS)  Please let me know (support@applette.com) if you would be interested in trying this when I have the beta available (the beta will be free) and I will keep you informed.

So why bother with GPRS?

In terms of which method is better, I guess it comes down to which of the following apply/are important to you:

  • SMS mode can be directly displayed on your Phone by TKMon etc. without you having to do anything. i.e. it is quick and easy.
  • GSM SMS text coverage is often better in remote areas than GPRS.
  • SMS does not require you to leave potentially sensitive position information on a third party server.
  • SMS messages may be relatively expensive depending upon your carrier package and how many updates you are planning to do.
  • GPRS mode – currently requires an external service provider who runs a server at a fixed IP address who will process your messages – some services are free for small volumes others will charge you. You will also normally need to log in using a browser (you can do this on your phone usually) to actually see the map.
  • GPRS mode may be cheaper if you have a cheap data package from your cellular carrier (the amount of data needed is relatively small) and you are planning on receiving many position updates
  • In GPRS mode, some TK devices allow you to store position data when the GPRS server is unavailable. This information can then be uploaded to a server when the GPRS connection is restored.