GPON OLT C+/C+MAX modules are used for realization of point-multipoint connections through GPON technology. Most of GPON OLT devices has unpopulated SFP slots, thus it is possible to scale the device capabilities to actual needs. When owner of the OLT wants to connect new group of clients then he just adds another GPON SFP module to the OLT. That kind of modules supports assymetrical speeds (2.488Gbps/1.244Gbps). To allow bidirectional communication over single strain of fiber WDM technology was adopted (1310nm and 1490nm wavelengths are used).