Crate and Barrel stores are a unique mix of Avaya and Cisco. Most stores seem to use Avaya sets but a few random locations have Cisco 7900 sets. Crate and Barrel has long been an Avaya/Lucent/ATT user, and even some new stores are still installing legacy phone such as these 4412 sets.
The 4400 series were a short lived digital telephone portfolio (that worked on the Merlin Magix system) that were introduced around 1999 and replaced as soon as 2006 by the 2400 series telephones as Avaya was beginning to shift Merlin Magix customers to the IP Office. The Merlin Magix was officially phased out in 2006 and replaced by the IP Office. The 4400 is still supported on most versions of IP Office, so you can potentially upgrade your older Magix to a newer IP Office and keep your 4400 series phones.
The first time I saw these phones was at a Galyans Trading Company sporting goods store in Grand Rapids, MI in 2000. I thought the sets looked so state of the art and the paging sounded great. Unfortunately, the phone system has been phased out, Galayns was bought out by Dicks Sporting Goods and Dicks banned overhead paging in their stores. No fun.