[PHP] instant messenger php + ajax

hi i am looking for an instant messenger for my web site i would like to enable also not register user to chat to the other not register user in my web site.. where i can find a source code like this ?

[PHP] Instant messenger

Hi, I wanna create an instant private messenger. This kind of IM i have seen on dating sites. I've googled for such IM but i found nothing. Can someone please help me with this? Thank you