RFCOMM_FRAME_SABM
err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_SABM, pn.dlci);
err = rfcomm_session_send_frame(rs, RFCOMM_FRAME_SABM, 0);
RFCOMM_FRAME_SABM, dlc->rd_dlci);
case RFCOMM_FRAME_SABM: