PHP Ping Service

I want my own ping service script (like [login to view URL] etc.). must be written in and compatible to php 4.x. You don't need to design any front-end. Only the ping service script is needed. - Blogs/Websites can send a ping and the script receives it and parses it - Blocking spam and prevent spammers from mass-pinging - Must be safe, stable and using less cpu / server resources; expecting thousands of pings per hour - You must be familiar with XML RPC / XML / PHP !!! You must be available via instant messanger (yahoo/aim/msn/icq) during business hours for support. PS. XML::RPC Pear package is installed on our server.