Developed specifically to meet the needs of small and medium businesses, the Avaya 5400 series (this includes the 5402, 5410, and 5420 sets) of digital telephones incorporates sleek design, improved ergonomics, flexibility and enterprise-class voice quality. These two-wire digital telephones are designed for use with Avaya IP Office.
http://www.digitcom.ca/index.asp?PageAction=VIEWCATS&Category=23