More control over physical desk phone display name

It would be nice to have more control over the desk phone line display and internal caller display name. Right now the phone's use the 'firstname' and 'lastname' fields on the Admin portal, which is fine for organizational purposes, but lacks from a phone display standpoint. IE. "John Smith" is great for managing our user list, but on his actual phone and internal calling name I might want to display "John - Ext 6000". I know I can modify the first and lastname fields respectively, but that creates a very disorganized admin portal.