Bill -
Manual means you had to lift the handset and then press a signal key to ring the other end. It was considered a more reliable method of signalling then automatic which just required you to lift the handset to signal.
If all you want to do is to signal from the back door then automatic is the way to go. If you have a 416 then by all means - use it! Set the back door to be the distant (automatic side). If you don't have a 416 you would need TWO 415s or one 4415. PM me if you want a 4415, I have a couple in the dreaded basement. (The 4415 was not a 1A2 KTU - it was just a box about the size of a trade paperback that wired to the KSU)
If you're looking for something newer, slicker and more modern I believe Viking makes an door answering systemn that will work with 1A2. Sandman has one too (
www.sandman.com - search for 'door box'). Both of those systems have a speakerphone in a door plate with button so you wouldn't have to hang a phone outside.
Sam
