You seem to have libiconv in your system. Where is it located and is that location in LD_LIBRARY_PATH? (or /etc/ld.so.conf* file or directory..)

it's /usr/local/lib

This is wrong way to pass base install dir:
-with-curl=/usr/local/lib 

This is the correct way:

-with-curl=/usr/local

Fix these in your configure line. (There is no --with/--enable option in PHP configure that expects it to have /lib in the path!)

I edited the configure file, so it looks like that:

#!/bin/sh
./configure \
        --with-apxs2 \
        --with-curl \
        --with-curl=/usr/local \
        --with-gd \
        --with-gettext \
        --with-jpeg-dir=/usr/local/lib \
        --with-kerberos \
        --with-openssl \
        --with-mcrypt \
        --with-mhash \
        --with-mysql=/usr \
        --with-pear \
        --with-png-dir=/usr/local/lib \
        --with-xml \
        --with-zlib \
        --with-zlib-dir=/usr/local/lib \
        --with-zip \
        --enable-bcmath \
        --enable-calendar \
        --enable-ftp \
        --enable-magic-quotes \
        --enable-sockets \
        --enable-track-vars \
        --enable-mbstring \
        --enable-memory-limit \
        --enable-libxml


But I still get the same error when i try to compile it:

/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/iconv.c:1242: undefined                                                                              reference to `libiconv'
ext/iconv/.libs/iconv.o:/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/                                                                             iconv.c:1286: more undefined references to `libiconv' follow
ext/iconv/.libs/iconv.o: In function `php_iconv_stream_filter_ctor':
/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/iconv.c:2426: undefined                                                                              reference to `libiconv_open'
collect2: ld returned 1 exit status
make: *** [sapi/cli/php] Error 1
[root@server customapache]#

I meant EVERY option in PHP configure, not just the one.
Anyway, try this short version instead:

# rm config.cache && ./configure && make

When I changed all /usr/local/lib to /usr/local I had the same error as before, when I used rm config.cache && ./configure && make I got the following error:

/usr/local/directadmin/customapache/php-5.2.4/main/rfc1867.c:1185: undefined reference to `php_mb_gpc_encoding_converter'
main/.libs/output.o: In function `php_ob_init_named':
/usr/local/directadmin/customapache/php-5.2.4/main/output.c:438: undefined reference to `php_ob_gzhandler_check'
collect2: ld returned 1 exit status
make: *** [sapi/cgi/php-cgi] Error 1

Of course you should do "make clean", I forgot to mention that:

# rm config.cache && ./configure && make clean && make

still the same error :/

/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/iconv.c:1242: undefined reference to `libiconv'
ext/iconv/iconv.o:/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/iconv.c:1286: more undefined references to `libiconv' follow
ext/iconv/iconv.o: In function `php_iconv_stream_filter_ctor':
/usr/local/directadmin/customapache/php-5.2.4/ext/iconv/iconv.c:2426: undefined reference to `libiconv_open'
collect2: ld returned 1 exit status
make: *** [sapi/cgi/php-cgi] Error 1

What does this output:
# grep ICONV main/php_config.h 

grep: main/php_config.h: No such file or directory

Try find that file first. It's $top_builddir/main/php_config.h

Here's the output of # grep ICONV main/php_config.h after 'compilation':

[root@server php-5.2.4]# grep ICONV main/php_config.h
/* #undef HAVE_LIBICONV */
/* #undef HAVE_GICONV_H */
/* #undef HAVE_LIBICONV */
#define HAVE_ICONV 1
#define PHP_ICONV_IMPL "glibc"
/* #undef HAVE_BSD_ICONV */
#define PHP_ICONV_IMPL "glibc"
#define HAVE_GLIBC_ICONV 1
#define PHP_ICONV_IMPL "glibc"
#define ICONV_SUPPORTS_ERRNO 0
#define ICONV_SUPPORTS_ERRNO 0
#define ICONV_SUPPORTS_ERRNO 0
#define PHP_ICONV_H_PATH </usr/local/include/iconv.h>
/* #undef COMPILE_DL_ICONV */
/* #undef HAVE_LIBICONV */
/* #undef HAVE_GICONV_H */
/* #undef HAVE_LIBICONV */
#define HAVE_ICONV 1
[root@server php-5.2.4]#

Is there some reason you have libiconv installed in /usr/local when your glibc provides the same stuff? Did something else require it? As the fix is to simply uninstall libiconv..

No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".

Whenever you see "undefined reference to `libiconv_open'", try

make CFLAGS=-liconv

I have used --without-iconv with ./configure and make worked fine.

Hope it will work for you too.

-Milind ( http://trulymanaged.com )

To fix the error:
undefined reference to `libiconv_open'

Run configure like this:
[root@david php-5.2.4]# ./configure CFLAGS=-liconv

I used EXTRA_CFLAGS=-liconv instead of just CFLAGS=liconv