Toshiba TECRA M4 User Manual page 255

* EC stands for the Error Control method, which appears only when the
extended result codes configuration option is enabled. EC is replaced by
one of the following symbols, depending on the error control method
used.
V42bis
V42
NoEC
AT Command
-V90=*
-V90=0
-V90=1
User's Manual
V.42 error control and V.42bis data compression
V.42 error control only
No error control protocol
V.90 Dial Line Rate
-V90 sets the maximum V.90 downstream that the
modem attempts to connect.
V.90 disabled
V.90 enabled: automatic speed selection -
maximum modem speed (default)
V.90
E-3