Yeah, so you know that confusing bunch of Aastra cords with the colored ends? The mumbly jumbly one with all of the plug-in points? The one that looks like spaghetti? Color-coded spaghetti?

Yeah. That weird one.
Well, good news! Leitner headsets don’t use it! Woohoo!
If you’re looking for an Aastra hookswitch, check your Aastra telephone’s compat here.