The use of Multimode fibers (MMFs) in the low-frequency region has been studied. It is found that many available low-frequency passbands can be used as channels. However, these passbands are frequency-selective channels, which can negatively affect to the transmitted signal. To lessen this effect, Linear Block Code (LBC) along with a careful selection of passbands is applied. In this work, the performance in terms of BER and data rate for an MMF communication system using a 1-km length MMF at low-frequency passbands with different schemes of LBC is studied. This study uses subcarrier multiplexing (SCM) with a 3-dB modal bandwidth and other low-frequency passbands as channels. The results show that by using (31, 26) LBC and Type-I bit allocation, a data rate of 494 Mbps can be obtained with a BER lower than 10-9. Moreover, a BER lower than 10-14 can be achieved with a data rate of 399 Mbps, which is two-fold higher than the data rate obtained using only the 3-dB modal bandwidth. Additionally, the BER versus data rate for different cases in terms of applying LBC to the system are found and can be practically used as a guideline in selecting a BER and data rate that are suitable for the minimum requirement of a given communication system.