In order to use the CURL functions you need to install the CURL package. PHP requires that you use CURL 7.0.2-beta or higher. PHP will not work with any version of CURL below version 7.0.2-beta. In PHP 4.2.3, you will need CURL version 7.9.0 or higher. From PHP 4.3.0, you will need a CURL version that's 7.9.8 or higher. PHP 5.0.0 will most likely require a CURL version greater than 7.10.5