The Xerox Phaser 5500 was introduced in November 2004. It was positioned as a replacement for both the Phaser 5400 and DocuPrint® N4525 models. At the time of release its 50 page per minute (ppm) print speed was the fastest of Xerox’s network printers.
Four years later (May 2008) the Phaser 5550 replaced the 5500. The 5550 printed at the same speed (50 ppm), but offered twice the hard-drive capacity and higher maximum memory, as well as several new features. Supplies for the 5550 were upgraded, with toner units yielding up to 35,000 pages (30,000 pages for the 5500).
Lexmark also released their own version, the W840, based on the same print engine. Printers from both OEMs will not function properly without a chip (or with a spent chip) installed on both the toner and drum units.