+#ifndef CMX_TXDATA_ON
+#define OLD_MISDN
+#endif
+#ifndef CMX_TXDATA_OFF
+#define OLD_MISDN
+#endif
+#ifndef CMX_DELAY
+#define OLD_MISDN
+#endif
+#ifndef PIPELINE_CFG
+#define OLD_MISDN
+#endif
+#ifndef CMX_TX_DATA
+#define OLD_MISDN
+#endif
+
+#ifdef OLD_MISDN
+#warning
+#warning *********************************************************
+#warning *
+#warning * It seems that you use an older version of mISDN.
+#warning * Features like voice recording or echo will not work.
+#warning * Also it causes problems with loading modules and may
+#warning * not work at all.
+#warning *
+#warning * Please upgrade to newer version. A working version can
+#warning * be found at www.linux-call-router.de.
+#warning *
+#warning * Do not use the mISDN_1_1 branch, it does not have all
+#warning * the features that are required. Use the master branch
+#warning * instead.
+#warning *
+#warning *********************************************************
+#warning
+#error
+#endif
+