Summary form only given. Frequency conversion with efficiency and SNR degradation compatible with applications in optical networks has recently been obtained in optimized semiconductor optical amplifiers (SOAs) by four-wave mixing (FWM). Many problems remain however to be solved for practical applications. First, the efficiency of the conversion from high to low frequencies is low, often lower than required, because of the destructive interference between the different processes contributing to FWM. Second, most applications do not tolerate that efficiency varies as much as 10 dBs for conversion interval ranging from few tens of GHz to 2 THz. Third, a bandpass filter is required to select the converted signal at the converter output, which must be tunable if the destination frequency and/or the signal frequency change during network operation. A tunable filter is also required at the converter input to filter out the amplified spontaneous emission generated by the in-line amplifiers upstream over the bandwidth of the converted signal. Finally, the signal cannot be converted over the same frequency when FWM is used for mid-span spectral inversion. Conversion over the same frequency is desirable to avoid waste of bandwidth in systems where the bandwidth is limited by in-line erbium amplifiers. We propose a two-pump FWM scheme that solves the above problems all at once.