Fujitsu FMW4503TS128A01 manual Command Specification Default

Command			Specification	Default
		=21	Attempt to connect at 53333bit/s
		=?	Shows the current value.
		?	Shows the range [0-21]
%C	0	V.42bis/MNP5 disable. No data compression.
	1	V.42bis/MNP5 enable. Data compression enabled.		3
%E	0	Disable line quality monitor and auto-retrain.
	1	Enable line quality monitor and auto-retrain.
	2	Enable line quality monitor and fall back/fall forward.		3

AT Commands Table 84