On Thu, 1 Dec 2011, "James Harper" <james.harper@bendigoit.com.au> wrote:
A smart phone talking to a GSM modem attached to a fixed roadside device actually. They just don't want to have a separate GSM modem for the PC/laptop when they have a perfectly functional iPhone which they always have on them. Ultimately they will probably be using Windows to make the connection, but I'm testing with Linux. Because it's better :)
What does "GSM modem" really mean in this situation? There is no requirement to use the ISP Internet service to transfer packet/stream data over GSM. Some years ago some people I knew developed encrypted GSM phones which encrypted the encoded voice data and then sent it in the same way that regular GSM voice data is sent. The phones usually encode voice to data, compress it, and then GSM provides the ordered packet layer. Well they just added an extra encryption step. There's no technical obstacle to running something like PPP or a virtual serial port instead of encrypted voice in that situation, and the people I knew probably developed just that as a first stage towards their end goal. There's lots of different ways of doing these things, many of which can save a few dollars each on the cost of the multitude of devices in the field while adding to the hassle at the server end. Most of these things would be impractical to try and reverse engineer unless you have a great desire to learn about mobile phones. Of course such things would preclude using an iPhone as they are too locked down to be convenient for such things. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/