It currently displays the current desk phone/ Softphone presence, turns red when you are on a call.
Panasonic KX-TS880B Corded Feature Speakerphone with Caller ID in Black - Discontinued
AT&T 4-Line basic expandable corded telephone - DISCONTINUED
AT&T CL-2940 Corded Speakerphone with Display - BLACK
Cortelco C66 4 Line IP Business Telephone
Cortelco 9225 2 Line Telephone