diff --git a/acinclude.m4 b/acinclude.m4
index 1363a9e201..ca589d3122 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -380,13 +380,22 @@ if test "${HAS_OPENH323:-unset}" = "unset" ; then
   AC_CHECK_HEADER(${PWLIBDIR}/../openh323/version.h, OPENH323DIR="${PWLIBDIR}/../openh323"; HAS_OPENH323=1, )
   if test "${HAS_OPENH323:-unset}" != "unset" ; then
     OPENH323DIR="${PWLIBDIR}/../openh323"
-    AC_CHECK_HEADER(${OPENH323DIR}/include/h323.h, , OPENH323_INCDIR="${PWLIB_INCDIR}/openh323"; OPENH323_LIBDIR="${PWLIB_LIBDIR}")
+    saved_cppflags="${CPPFLAGS}"
+    CPPFLAGS="${CPPFLAGS} -I${PWLIB_INCDIR}/openh323 -I${PWLIB_INCDIR}"
+    AC_CHECK_HEADER(${OPENH323DIR}/include/h323.h, , OPENH323_INCDIR="${PWLIB_INCDIR}/openh323"; OPENH323_LIBDIR="${PWLIB_LIBDIR}", [#include <ptlib.h>])
+    CPPFLAGS="${saved_cppflags}"
   else
+    saved_cppflags="${CPPFLAGS}"
+    CPPFLAGS="${CPPFLAGS} -I${HOME}/openh323/include -I${PWLIB_INCDIR}"
     AC_CHECK_HEADER(${HOME}/openh323/include/h323.h, HAS_OPENH323=1, )
+    CPPFLAGS="${saved_cppflags}"
     if test "${HAS_OPENH323:-unset}" != "unset" ; then
       OPENH323DIR="${HOME}/openh323"
     else
+      saved_cppflags="${CPPFLAGS}"
+      CPPFLAGS="${CPPFLAGS} -I/usr/local/include/openh323 -I${PWLIB_INCDIR}"
       AC_CHECK_HEADER(/usr/local/include/openh323/h323.h, HAS_OPENH323=1, )
+      CPPFLAGS="${saved_cppflags}"
       if test "${HAS_OPENH323:-unset}" != "unset" ; then
         OPENH323DIR="/usr/local/share/openh323"
         OPENH323_INCDIR="/usr/local/include/openh323"
@@ -396,7 +405,10 @@ if test "${HAS_OPENH323:-unset}" = "unset" ; then
           OPENH323_LIBDIR="/usr/local/lib"
         fi
       else
-        AC_CHECK_HEADER(/usr/include/openh323/h323.h, HAS_OPENH323=1, )
+        saved_cppflags="${CPPFLAGS}"
+        CPPFLAGS="${CPPFLAGS} -I/usr/include/openh323 -I${PWLIB_INCDIR}"
+        AC_CHECK_HEADER(/usr/include/openh323/h323.h, HAS_OPENH323=1, , [#include <ptlib.h>])
+        CPPFLAGS="${saved_cppflags}"
         if test "${HAS_OPENH323:-unset}" != "unset" ; then
           OPENH323DIR="/usr/share/openh323"
           OPENH323_INCDIR="/usr/include/openh323"
diff --git a/configure b/configure
index eddd747295..6b5e36bdf8 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.ac Revision: 76296 .
+# From configure.ac Revision: 76523 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61.
 #
@@ -31482,27 +31482,22 @@ fi
 
   if test "${HAS_OPENH323:-unset}" != "unset" ; then
     OPENH323DIR="${PWLIBDIR}/../openh323"
+    saved_cppflags="${CPPFLAGS}"
+    CPPFLAGS="${CPPFLAGS} -I${PWLIB_INCDIR}/openh323 -I${PWLIB_INCDIR}"
     as_ac_Header=`echo "ac_cv_header_${OPENH323DIR}/include/h323.h" | $as_tr_sh`
-if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
-  { echo "$as_me:$LINENO: checking for ${OPENH323DIR}/include/h323.h" >&5
+{ echo "$as_me:$LINENO: checking for ${OPENH323DIR}/include/h323.h" >&5
 echo $ECHO_N "checking for ${OPENH323DIR}/include/h323.h... $ECHO_C" >&6; }
 if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
-fi
-ac_res=`eval echo '${'$as_ac_Header'}'`
-	       { echo "$as_me:$LINENO: result: $ac_res" >&5
-echo "${ECHO_T}$ac_res" >&6; }
 else
-  # Is the header compilable?
-{ echo "$as_me:$LINENO: checking ${OPENH323DIR}/include/h323.h usability" >&5
-echo $ECHO_N "checking ${OPENH323DIR}/include/h323.h usability... $ECHO_C" >&6; }
-cat >conftest.$ac_ext <<_ACEOF
+  cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
 _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-$ac_includes_default
+#include <ptlib.h>
+
 #include <${OPENH323DIR}/include/h323.h>
 _ACEOF
 rm -f conftest.$ac_objext
@@ -31522,94 +31517,19 @@ eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
 	 test -z "$ac_cxx_werror_flag" ||
 	 test ! -s conftest.err
        } && test -s conftest.$ac_objext; then
-  ac_header_compiler=yes
+  eval "$as_ac_Header=yes"
 else
   echo "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_header_compiler=no
+	eval "$as_ac_Header=no"
 fi
 
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-{ echo "$as_me:$LINENO: result: $ac_header_compiler" >&5
-echo "${ECHO_T}$ac_header_compiler" >&6; }
-
-# Is the header present?
-{ echo "$as_me:$LINENO: checking ${OPENH323DIR}/include/h323.h presence" >&5
-echo $ECHO_N "checking ${OPENH323DIR}/include/h323.h presence... $ECHO_C" >&6; }
-cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include <${OPENH323DIR}/include/h323.h>
-_ACEOF
-if { (ac_try="$ac_cpp conftest.$ac_ext"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
-  (eval "$ac_cpp conftest.$ac_ext") 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } >/dev/null && {
-	 test -z "$ac_cxx_preproc_warn_flag$ac_cxx_werror_flag" ||
-	 test ! -s conftest.err
-       }; then
-  ac_header_preproc=yes
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-  ac_header_preproc=no
-fi
-
-rm -f conftest.err conftest.$ac_ext
-{ echo "$as_me:$LINENO: result: $ac_header_preproc" >&5
-echo "${ECHO_T}$ac_header_preproc" >&6; }
-
-# So?  What about this header?
-case $ac_header_compiler:$ac_header_preproc:$ac_cxx_preproc_warn_flag in
-  yes:no: )
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: accepted by the compiler, rejected by the preprocessor!" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: accepted by the compiler, rejected by the preprocessor!" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: proceeding with the compiler's result" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: proceeding with the compiler's result" >&2;}
-    ac_header_preproc=yes
-    ;;
-  no:yes:* )
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: present but cannot be compiled" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: present but cannot be compiled" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h:     check for missing prerequisite headers?" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h:     check for missing prerequisite headers?" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: see the Autoconf documentation" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: see the Autoconf documentation" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h:     section \"Present But Cannot Be Compiled\"" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h:     section \"Present But Cannot Be Compiled\"" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: proceeding with the preprocessor's result" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: proceeding with the preprocessor's result" >&2;}
-    { echo "$as_me:$LINENO: WARNING: ${OPENH323DIR}/include/h323.h: in the future, the compiler will take precedence" >&5
-echo "$as_me: WARNING: ${OPENH323DIR}/include/h323.h: in the future, the compiler will take precedence" >&2;}
-
-    ;;
-esac
-{ echo "$as_me:$LINENO: checking for ${OPENH323DIR}/include/h323.h" >&5
-echo $ECHO_N "checking for ${OPENH323DIR}/include/h323.h... $ECHO_C" >&6; }
-if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
-  echo $ECHO_N "(cached) $ECHO_C" >&6
-else
-  eval "$as_ac_Header=\$ac_header_preproc"
 fi
 ac_res=`eval echo '${'$as_ac_Header'}'`
 	       { echo "$as_me:$LINENO: result: $ac_res" >&5
 echo "${ECHO_T}$ac_res" >&6; }
-
-fi
 if test `eval echo '${'$as_ac_Header'}'` = yes; then
   :
 else
@@ -31617,7 +31537,10 @@ else
 fi
 
 
+    CPPFLAGS="${saved_cppflags}"
   else
+    saved_cppflags="${CPPFLAGS}"
+    CPPFLAGS="${CPPFLAGS} -I${HOME}/openh323/include -I${PWLIB_INCDIR}"
     as_ac_Header=`echo "ac_cv_header_${HOME}/openh323/include/h323.h" | $as_tr_sh`
 if { as_var=$as_ac_Header; eval "test \"\${$as_var+set}\" = set"; }; then
   { echo "$as_me:$LINENO: checking for ${HOME}/openh323/include/h323.h" >&5
@@ -31751,9 +31674,12 @@ if test `eval echo '${'$as_ac_Header'}'` = yes; then
 fi
 
 
+    CPPFLAGS="${saved_cppflags}"
     if test "${HAS_OPENH323:-unset}" != "unset" ; then
       OPENH323DIR="${HOME}/openh323"
     else
+      saved_cppflags="${CPPFLAGS}"
+      CPPFLAGS="${CPPFLAGS} -I/usr/local/include/openh323 -I${PWLIB_INCDIR}"
       if test "${ac_cv_header__usr_local_include_openh323_h323_h+set}" = set; then
   { echo "$as_me:$LINENO: checking for /usr/local/include/openh323/h323.h" >&5
 echo $ECHO_N "checking for /usr/local/include/openh323/h323.h... $ECHO_C" >&6; }
@@ -31884,6 +31810,7 @@ if test $ac_cv_header__usr_local_include_openh323_h323_h = yes; then
 fi
 
 
+      CPPFLAGS="${saved_cppflags}"
       if test "${HAS_OPENH323:-unset}" != "unset" ; then
         OPENH323DIR="/usr/local/share/openh323"
         OPENH323_INCDIR="/usr/local/include/openh323"
@@ -31893,25 +31820,21 @@ fi
           OPENH323_LIBDIR="/usr/local/lib"
         fi
       else
-        if test "${ac_cv_header__usr_include_openh323_h323_h+set}" = set; then
-  { echo "$as_me:$LINENO: checking for /usr/include/openh323/h323.h" >&5
+        saved_cppflags="${CPPFLAGS}"
+        CPPFLAGS="${CPPFLAGS} -I/usr/include/openh323 -I${PWLIB_INCDIR}"
+        { echo "$as_me:$LINENO: checking for /usr/include/openh323/h323.h" >&5
 echo $ECHO_N "checking for /usr/include/openh323/h323.h... $ECHO_C" >&6; }
 if test "${ac_cv_header__usr_include_openh323_h323_h+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
-fi
-{ echo "$as_me:$LINENO: result: $ac_cv_header__usr_include_openh323_h323_h" >&5
-echo "${ECHO_T}$ac_cv_header__usr_include_openh323_h323_h" >&6; }
 else
-  # Is the header compilable?
-{ echo "$as_me:$LINENO: checking /usr/include/openh323/h323.h usability" >&5
-echo $ECHO_N "checking /usr/include/openh323/h323.h usability... $ECHO_C" >&6; }
-cat >conftest.$ac_ext <<_ACEOF
+  cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
 _ACEOF
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
-$ac_includes_default
+#include <ptlib.h>
+
 #include </usr/include/openh323/h323.h>
 _ACEOF
 rm -f conftest.$ac_objext
@@ -31931,98 +31854,24 @@ eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
 	 test -z "$ac_cxx_werror_flag" ||
 	 test ! -s conftest.err
        } && test -s conftest.$ac_objext; then
-  ac_header_compiler=yes
+  ac_cv_header__usr_include_openh323_h323_h=yes
 else
   echo "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_header_compiler=no
+	ac_cv_header__usr_include_openh323_h323_h=no
 fi
 
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-{ echo "$as_me:$LINENO: result: $ac_header_compiler" >&5
-echo "${ECHO_T}$ac_header_compiler" >&6; }
-
-# Is the header present?
-{ echo "$as_me:$LINENO: checking /usr/include/openh323/h323.h presence" >&5
-echo $ECHO_N "checking /usr/include/openh323/h323.h presence... $ECHO_C" >&6; }
-cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-#include </usr/include/openh323/h323.h>
-_ACEOF
-if { (ac_try="$ac_cpp conftest.$ac_ext"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
-  (eval "$ac_cpp conftest.$ac_ext") 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } >/dev/null && {
-	 test -z "$ac_cxx_preproc_warn_flag$ac_cxx_werror_flag" ||
-	 test ! -s conftest.err
-       }; then
-  ac_header_preproc=yes
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-  ac_header_preproc=no
-fi
-
-rm -f conftest.err conftest.$ac_ext
-{ echo "$as_me:$LINENO: result: $ac_header_preproc" >&5
-echo "${ECHO_T}$ac_header_preproc" >&6; }
-
-# So?  What about this header?
-case $ac_header_compiler:$ac_header_preproc:$ac_cxx_preproc_warn_flag in
-  yes:no: )
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: accepted by the compiler, rejected by the preprocessor!" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: accepted by the compiler, rejected by the preprocessor!" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: proceeding with the compiler's result" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: proceeding with the compiler's result" >&2;}
-    ac_header_preproc=yes
-    ;;
-  no:yes:* )
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: present but cannot be compiled" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: present but cannot be compiled" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h:     check for missing prerequisite headers?" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h:     check for missing prerequisite headers?" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: see the Autoconf documentation" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: see the Autoconf documentation" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h:     section \"Present But Cannot Be Compiled\"" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h:     section \"Present But Cannot Be Compiled\"" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: proceeding with the preprocessor's result" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: proceeding with the preprocessor's result" >&2;}
-    { echo "$as_me:$LINENO: WARNING: /usr/include/openh323/h323.h: in the future, the compiler will take precedence" >&5
-echo "$as_me: WARNING: /usr/include/openh323/h323.h: in the future, the compiler will take precedence" >&2;}
-
-    ;;
-esac
-{ echo "$as_me:$LINENO: checking for /usr/include/openh323/h323.h" >&5
-echo $ECHO_N "checking for /usr/include/openh323/h323.h... $ECHO_C" >&6; }
-if test "${ac_cv_header__usr_include_openh323_h323_h+set}" = set; then
-  echo $ECHO_N "(cached) $ECHO_C" >&6
-else
-  ac_cv_header__usr_include_openh323_h323_h=$ac_header_preproc
 fi
 { echo "$as_me:$LINENO: result: $ac_cv_header__usr_include_openh323_h323_h" >&5
 echo "${ECHO_T}$ac_cv_header__usr_include_openh323_h323_h" >&6; }
-
-fi
 if test $ac_cv_header__usr_include_openh323_h323_h = yes; then
   HAS_OPENH323=1
 fi
 
 
+        CPPFLAGS="${saved_cppflags}"
         if test "${HAS_OPENH323:-unset}" != "unset" ; then
           OPENH323DIR="/usr/share/openh323"
           OPENH323_INCDIR="/usr/include/openh323"