What exactly does the Ciena 3930 do?

Originally and for many years we had dedicated fiber, with an onsite Ciena 3930 doing all the work. It was attached to a fiber pair from the street, and then to my router using a ethernet cable. Eventually we switched over to business fiber (ABF). The Ciena is now connected to one fiber pair from the street, and another fiber pair to a BGW320. I believe there is no GPON or or XGS-GPON anywhere, and everything is active ethernet. The BGW320 reports its WAN connection as 1000BASE-LX with wavelength 1310nm. I have sneaking suspicion that the Ciena 3930 is not doing anything at all. What would happen if I bypassed it completely, and connected the fiber pair from the street directly into the BGW320? All of the SFP handle colors are the same (blue) and there are no other customers using the Ciena. If it truly is not doing anything I would love to reduce noise and power consumption by removing it from service. If it is doing something useful, I would love to know what.