We need a system which can interract with a GSM mobile/modem and via audio channel to be able to send data (it's like a modem on a carrier).
The problem is that the GSM voice channel isn' a simple carrier - the audio is entered in a lossy AMR codec.
We need to transfer data with a bandwidth of 2400 bytes/sec - actually the audio is at codec's input with resolution of 8000 frames/sec - 16 bit width.
The system we need must be on this voice carrier because in many countries the CSD line service isn't easily available (this service has a bandwidth of 9600bits/sec) - we need fewer BUT on the voice channel.
The GPRS also isn't a good solution for us because requires session establishing, the service isn;t so cheap in many countries/providers and especially at prepaired sim cards.
The final solution must be provided like a PC software which can send/receive data connected to a GSM phone/modem - 2 PC's and 2 phones which are involved in a voice call.
The connection with PC can be made through the soundcard or better via Bluetooth - on a SCO connection - like used in HFP profile.
Or better a Windows Mobile C++ application.
The project should be similar to [url removed, login to view] but with higher performance for data transfer.
BEFORE BIDDING the author should provide evidence of strong knowledge in DSP area and provide also which is the concept and idea, as there are only a couple of method that we already know to implement this.
If the seller don't know about it and can't provide that knowledge as a reference please DON'T BID!