Chat on Webiste 1:n instead of n:m communication

[stony999]

I want to achiven the following:
- A central admin can chat to all users on a website. He is subscribed
to all channels
- Users may be identified by their IP address, and then they can
subscribe to a channel, which can contain their IP address
- when the admin receives a message from a user A on a channel A, he
can answer through this channel A to the user A who sent the message
- when the admin receives a message from a user B on a channel B, he
can answer through this channel B to the user B who sent the message
- user A cannot see messages of user B

This may be simple with various chat windows for the agent. But as IP
addresses change, it's hard to identify distinct channel names. And I
think, it's easier when the admin has just one windows to answer on
the requests.

Question: Has anybody already developed such a solution and can give
me some directions, how to start this?