The libcapi20-3 package was carved out from the long-established isdnutils
package for easier maintenance in March 2014.  Feel free to consult isdnutils
history to learn more about how things evolved prior to that date.

It may become necessary to debug libcapi20. Debian builds the package without
debug information for performance reasons.  Below patch will compile the
library with debug information.

diff --git a/capi20/capi20.c b/capi20/capi20.c
index ab8c1c6..81b5c5c 100644
--- a/capi20/capi20.c
+++ b/capi20/capi20.c
@@ -61,7 +61,7 @@ static int tracelevel;
 static char *tracefile;

 /** debug level, for debugging purpose */
-static int nDebugLevel = 0;
+static int nDebugLevel = 0xFFFF;

 /**
  * \brief CapiDebug output functions