V.34
Leased Line mode doesn't fall-back or fall-forward
between different modulation modes (i.e. V.34 to
V.32bis) and vice versa:
ITU-T standard V.34 supports speeds from
2400 to 28.8K bps; a range wide enough for users. Different
modulation fall-back and fall-forward are not in definition
and do not become necessary.
