A Magix processor can go in a clamshell using a Legend carrier.

Both the Legend and Magix only display one line of caller id. I know with the Magix, you can setup a button or dial a feature code to toggle between caller id name and number but it will only show one of the other at a time. The Legend may have the same feature, but I can't remember.

If you want both name and number on the display, your Avaya options are Partner ACS, or IP Office.