Retrieve data sent on network to a specific IP Address

I am trying to retrieve information sent to an IP address which is in my case an IP Phone. I would like to know if there is any free code or API calls that can let me read what's going to a specific IP address on the network so I can do something with it.

I think WireShark http://www.wireshark.org/ is what you want

No, I know what Wireshark is. I do not want to sniff the network.

Here is what I want, I want to retrieve information that tries to enter my phone to try and retrieve the phone number to do a search in a database we have here to show the customer's phone history before answering the phone.

I want to show who is calling on the phone next to my desk which has a seperate IP address than my computer and then treat that data as I wish for internal purposes.

If you're not on the same wire (or at least on a non-switched net) you have to get that information from either some software inside the phone in question or from the other end i.e. the caller or some local server or similar. Either place requires that you know what OS that runs in order to know how to intercept the ip-traffic.

Ok, that answers my question, I'm not connected on the same wire and it won't happen. So I'll need to find another solution.

Thanks a lot for your time in answering.