E4793 Cmd Rej: The parameter value can't be changed back to NONE
If a digit string value has already been specified for the mosmsgta or mtsmsdltrv parameter, then a value of none cannot be specified subsequently for that parameter.
Recovery
Display the current values for the parameters. Enter the rtrv-gsmsmsopts command.
Re-enter the chg-gsmsmsopts command that generated this error message, specifying a valid combination of parameters. Refer to the command description in Commands User's Guide and to MO-SMS User's Guide for assistance.