Hi Stefan,where can I find the specification of the BlueZ L2CAP and SDP API? I hope there ist any.the L2CAP API is a socket interface and you will find the API in the bluetooth/l2cap.h header file. For an usage example look at l2test. The SDP API can be found in bluetooth/sdp.h and bluetooth/sdp_lib.h and for example code look at the dund and pand applications.And how can I register my application for getting HCI events, so that I don't have to poll? hcid? API/specs?The HCI API is also a socket interface. If you want to have some kind of event based approach you have to use and IO event main loop like it is used in the Glib. Regards Marcel