Two-Way Chat (Web to Cell, via SMS)

Hi, Im looking for a programmer who is capable of developing Chat Applications in PHP. what I need is like 'Live Chat' on many webhosting sites, some IRC client or such as [login to view URL] Web Messenger Note: around 25000 users will use this Chat thing, so it needs to be well optimized. Links to Previous work are highly appreciated. More details about this project will be provided on behalf of Previous work Budget is around $500 (can increase a bit in needed)