Toshiba Satellite M40 User Manual page 227

AT Command
-V90=* V.90 Dial Line Rate
-V90 sets the maximum V.90 downstream that the modem attempts to
connect.
-V90=0 V.90 disabled
-V90=1 V.90 enabled: automatic speed selection - maximum modem speed
(default)
Appendix E
E-3