My girlfriend is visiting Dallas for work and she captured this older Lucent badged 6408D digital telephone.
The 6400 sets were introduced under the Lucent banner in 1997 which was changed to Avaya in 2000. The 6400 sets replaced the square designed 8400 series sets. The 6408 was a replacement for the 8410 digital set.
In my opinion, this is by far one of the finest designed digital telephones ever made. This set along with the Meridian M2008HF (which this set directly competed against) are probably some of the most solid and indestructible phones ever made by telecom providers. I also appreciate the aero styling on both telephones. Newer Avaya sets are flat boards, while these older sets had curves and styling that still looks good on many desks today.
It’s interesting to note that the styling of these 6400 phones closely resembled the styling of the M2000 series released in 1989 from Northern Telecom. Once Avaya came out with these sets in 1997, Nortel decided to take a dramatic departure from the vertical button oriented telephones with adjustable displays on the top. Thusly in 1998, Nortel introduced a large display M3900 series telephone platform, with self labeling LCD keys and wide horizontal telephone shape and base. This newer Nortel design made the Avaya 6400 sets look somewhat obsolete and the 2400 digital sets were introduced to compete with the new Nortel product.