The enormous potential of WDM technology is widely used in today's telecommunication networks. However, the economical factor makes WDM systems available only for application in long-haul systems with demand for high capacity (the order of Tbit/s) [1]. In case there was an affordable WDM system providing moderate data rates (the order of Gbit/s) it could be used for application in MANs (Metropolitan Area Networks) with fiber spans of up to 10 km. Using such a system telecom operators would be able to multiplex various technologies/services via one fiber, for example Ethernet for data services and STM-4 for telephony applications, or multiplex several physical (e.g. Ethernet) links for the purpose of greater capacity and/or reliability. In this paper we demonstrate a theoretical 4-channel spectrum-sliced WDM telecommunication system, utilizing LED sources with internal modulation and optical filtering (slicing) for channel separation.