This is not uncommon. It's a racket. Optics for all of the major network equipment manufacturers are made by a company named Finisar, regardless of the brand name on the transceiver.
There's a 256-byte EEPROM code block that is customized for each "manufacturer" (Finisar customer) as well as the sticker with the brand name. Other than that they're all identical inside.
Companies like Adtran, HP, and Cisco apply huge markups on "genuine" Finisar transceivers. Insanely huge markups.
For Adtran, try "no alarm enable pluggable unknown" in interface configuration mode, but beware that it doesn't work on all platforms. Cisco is "service unsupported-transceiver" in global mode. HP is "allow-unsupported-transceiver" in global mode.
If that doesn't work, buy from a Finisar reseller that can re-flash the EPROM to mimic Adtran's code, or bite the bullet and shell out the big bucks for a "genuine" transceiver.
You'll hear dire warnings from the network gear manufacturers about non-genuine transceivers causing pestilence, plague, famine, volcanoes, etc. Ignore them. You can buy a Finisar transceiver from a reseller coded for Adtran, Cisco, etc. and half a dozen spares for about the same money as one "genuine" one. Once the EEPROM is dialed in the only difference is the sticker (and the price).
