To build H.323 Plus see: 

1) Goto http://www.h323plus.org/source/

2) Download the H.323 Plus Core library for Linux, PWLib (PTLib) for Linux and the chan_h323 files for Asterisk trunk version. H323 Plus support for Asterisk's chan_h323 is currently tested with H.323 Plus v1.19.7 and PWLib (PTLib) v1.12.0

Now, assuming that you have un-tared PTLib in /usr/src/ptlib and H323Plus in /usr/src/h323plus do the following (change the directory paths as needed):

3) cd /usr/src/ptlib

4) ./configure

5) make opt (DO NOT make install!!!)

6) cd /usr/src/h323plus

7) ./configure --disable-h224 --disable-h230 (if there are problems with file permissions, do a 'chmod -R a+wrx ./*' before configuring)

8) make opt (DO NOT make install!!!)

9) Assuming that you have downloaded Asterisk trunk version in /usr/src/asterisk, replace the original files in the /usr/src/asterisk with those contained in the modified chan_h323 files. 

10) export PWLIBDIR=/usr/src/ptlib

11) export OPENH323DIR=/usr/src/h323plus

12) export LD_LIBRARY_PATH=$PWLIBDIR/lib:$OPENH323DIR/lib

13) cd /usr/src/asterisk

14) ./configure

15) make install as usual