The greatest advantage of metro ethernet is price. The monthly cost of EoC is about one third of the price of equivalent bandwidth delivered in the form of bonded T1 or fractional DS3. Also, because EoC and EoDS1 are delivered over regular copper phone lines, they normally do not require build-out. For this reason, they can often be installed for free, whereas fractional DS3 often requires build-out for buildings which are not lit. A third advantage of ethernet is that it requires far less sophisticated customer premise routing equipment. Ethernet provides an ethernet handoff that does not require expensive CSU/DSUs that are required for customer interfacing with T1 or DS3.