на одном сайте показывает iconv в нескольких местах
.......e-ftp’ ‘—with-freetype-dir=/usr’ ‘—with-png-dir=/usr’ ‘—with-dba’ ‘—with-zlib’ ‘—with-iconv’ ‘—with-expat’ ‘—enable-sysvshm’ ‘—enable-sysvsem’ ‘—enable-dbase’ ‘—enable-trans-sid’ ‘—without-xpm’ ‘—with-curl’ ‘—with-dom’ ‘—with-dom-xslt’ ‘—with-dom-exslt’ ‘—with-openssl-dir=/usr’ ‘—with-imap’ ‘—enable-mbstring’ ‘—enable-mbstring=all’ ‘—with-mcrypt’ ‘—with-gettext’ ‘—with-openssl’ ‘—with-pgsql’ ‘—with-xsl’ ‘—with-libxml-dir=/usr’ ‘—with-xmlrpc’ ‘—with-iconv-prefix=/usr’ ‘—enable-sigchild’ ‘—with-zlib-dir=/usr’ ‘—with-pdo-mysql’ ‘—with-mysqli’ ‘—enable-calendar’ ‘—enable-bcmath’ ‘—with-pdo-sqlite’ ‘—with-sqlite’ ‘—with-mssql’..........
Registered Stream Filters string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed, convert.[b]iconv[/b].*, zlib.*
iconv support enabled
iconv implementation glibc
iconv library version 2.3.3
Directive Local Value Master Value
iconv.input_encoding ISO-8859-1 ISO-8859-1
iconv.internal_encoding ISO-8859-1 ISO-8859-1
iconv.output_encoding ISO-8859-1 ISO-8859-1
на другом только
.............-enable-ctype’ ‘—enable-ftp’ ‘—with-gd’ ‘—enable-gd-native-ttf’ ‘—enable-gd-jis-conv’ ‘—with-freetype-dir=/usr/local’ ‘—with-jpeg-dir=/usr/local’ ‘—with-png-dir=/usr/local’ ‘—with-xpm-dir=/usr/local’ ‘—with-iconv-dir=/usr/local’ ‘—with-mime-magic=/usr/share/misc/magic.mime’ ‘—with-mysql=/usr/local’ ‘—enable-overload’ ‘—with-pcre-regex=yes’ ‘—enable-posix’ ‘—enable-session’ ‘—enable-tokenizer’ ‘—with-expat-dir=/usr/local’ ‘—enable-xml….........
перекомпилировать php… или переходить полностью на utf-8. 
