angelo_amadei:
*Arduino BT info: "The Arduino BT is a microcontroller board originally was based on the ATmega168, but now is supplied with the 328. (datasheet) and the Bluegiga WT11 bluetooth module (details and datasheet [pdf]). It supports wireless serial communication over bluetooth (but is not compatible with Bluetooth headsets or other audio devices)."...the problem is not the module used, the problem is that the arduino capabilities aren't sufficient, is that so?
Yes, that sounds correct. It sounds like the Arduino BT only supports SPP mode (Serial Port Protocol), whereas it needs to support HFP mode (Hands Free Protocol).
The bluetooth protocol is actually a collection of protocols and modes. Notice SPP and HFP serve two entirely different purposes. Many of the newer, full stereo bluetooth headsets require support for A2DP (Advanced Audio Distribution/Digital (forget) Protocol). Whereas many of the older bluetooth headsets support a different protocol (forget which), which is also far less capable and reliable.