public static int getTPDUService(final byte[] tpdu)
	{
		final int ctrl = tpdu[0] & 0xff;
		if ((ctrl & 0xFC) == 0)
			return 0;
		// 0x04 is tag_group service code, not used by us
		if ((ctrl & 0xFC) == 0x04)
			return 0x04;
		if ((ctrl & 0xC0) == 0x40)
			return T_DATA_CONNECTED;
		if (ctrl == T_CONNECT)
			return T_CONNECT;
		if (ctrl == T_DISCONNECT)
			return T_DISCONNECT;
		if ((ctrl & 0xC3) == T_ACK)
			return T_ACK;
		if ((ctrl & 0xC3) == T_NAK)
			return T_NAK;
		logger.warn("unknown TPCI service code 0x" + Integer.toHexString(ctrl));
		return ctrl;
	}