I have a 310 with my Parrot kit (great bit of kit is the MKi9200 which I have) and the answer to your question is nope it;s not built in to the 310, someone said the 315 has it built in and it is disabled and this maybe the same for the 310 but I don't have VAG-COM to try it and it's also not guaranteed.
Your options are to get something the the Parrot or get an official VW Bluetooth module for roughly £200-250.
Hope this helps!