 Where V.44 or V.42bis operate at layer 1 on the OSI model, MPPC operates on layer 2, giving it a significant advantage in terms of computing resources available to it.The dialup modem's in-built compression (V.44 or V.42bis) can only occur after the data has been serially transmitted to the modem, typically at a maximum rate of 115,200 bit/s.MPPC, as it is controlled by the operating system, can receive as much data as it wishes to compress, before forwarding it on to the modem.