Here are the format of SMDI messages used with MWI On/Off :

MWI On

OP:MWI<0X20>”stn-num”!<^D>

OP is used to indicate that MWI should be turned on for the specified station number and <^D> indicates an end of transmission.

MWI Off

RMV:MWI<0X20>”stn-number”!<^D>

RMV is used to request that MWI should be turned off the the specific station number