is it possible in Symbian OS to have a GSM voice call and send simultaneously data through the voice call channel? That is the user can receive/hear audio from the remote side and talk to the remote side and simultaneouly the phones exchange some data through the same GSM CSD channel as the voice call is using.
I know this sounds complex - but before voice is transmitted it is encoded using AMR, and the digital signal is transmitted through the network, right? I just want to add a few bytes to this AMR encoded signal. Is that possible? If no, why not? If yes, where to look (I will not be frightened by some low level complexity).
Sending the data through a simultaneous GPRS connection is no option for this project.