Here is a trick that we use for 2420's, create a short code for whatever you want, and just name the short code the decription instead of *81 or *90 ect. Works like a charm. We have a site with 300 2420's that "encouraged" us to burn the midnight oil to fix that issue. Here is an example:
We needed to make a Short Code for an Out Of Office Absent text
Short Code - Out Of Office
Tel Number - "1,1,Out Of Office"
Feature - Set Absent Text
Now the 2420 displays Out Of Office on its display.
You can do this for anything, but keep in mind that it will turn the speaker on, but not off. We are still working on that one.