A communication system in which probabilistic signal shaping and FEC coding are jointly used in an efficient manner that enables, e.g., the use of relatively high modulation orders without a penalizing increase of the FEC-code rate. In an example embodiment, the amplitudes of transmitted constellation symbols are generated using a shaping encoder. Some transmitted constellation symbols carry, as sign bits, the parity-bit values generated by an FEC encoder configured to operate on (i) a subset of bits from the binary labels of the shaped amplitudes and (ii) an additional set of unshaped information bits. Some other transmitted constellation symbols carry, as sign bits, the bit values of the additional set of unshaped information bits. In some embodiments the used FEC code can be a low-density parity-check code. Some embodiments can be used in communication systems relying on discrete multi-tone modulation, such as the systems providing DSL access over subscriber lines.