Hi Sunny,
In order to add Bluetooth and 3G support you need a Bluetooth chip dongle from a manufacturer like CSR and for 3G is the same.
There's some USB and UART dongles for Bluetooth and 3G like these ones:
Newegg.com - SYBA SY-ADA23012 Bluetooth 2.0 + EDR Dongle, CSR Chipset USB 2.0
Newegg.com - Huawei E173 WCDMA 3G USB Wireless Modem Dongle Adapter SIM TF Card HSDPA EDGE GPRS
Also both need a software stack in order to work properly. On the case of bluetooth exist bluez which is full functional open source stack which works on Linux. I don't know if there's one for 3G.
Also you need enable in your OS the support of low level protocols for example Bluetooth there's H4,BCSP,etc.
3G works with AT commands so the device should be detected as modem by your OS.
The audio on those devices is redirected by the link protocols or if the HW supports using pcm/i2s lines.
Be aware any wireless chip have a eeprom to store the firmware and that firmware contains the default setup of your
chip like baudrate, link protocol,supported features,etc. if you don't have access to the documentation of the firmware is going to be hard setup properly your OS driver and also change those parameters.
Also some upper layer setup need to be done. For example in Linux for Bluetooth you need to setup the Bluetooth server, the Bluetooth pairing agent, server audio to redirect streaming from Bluetooth device and maybe other server like https://ofono.org/ in order to redirect your call from your phone. All depends of your needs.
Regards,
-Israel.
