Hi we are planning to deploy an Access Edge Server just for the purpose of enabling our internal users be able to communicate to public IM. My question is do we need to deploy an Access Proxy as well and does it resides on a sepearte server as the Access Edge Server?
An Access Edge and Access Proxy are almost the same thing. In LCS 2005 it was called an Access Proxy and it only handled PIC, Remote Access and Federation. In OCS 2007 it's called an Access Edge and it performs the same functions (though there are other Edge roles that can be deployed with it).