Ha Ha, Yes I know it's tough to answer in few words , I am working on Meridian , but I need some concept on how the call flow happens so that I can understand the system better. You may think strange, I am working on this and still I am asking about how the things work. But Fred, In a pstn System once the call lands on to the trk lines , how do I get the welcome message then how does the digits enterd by the user is being taken on to system and transferd to the extension.