For this compact syntax to work the input and output need to follow specific naming rules
[(mobile)]="myParam"
@Output('mobileChange') emitter: EventEmitter<string> = new EventEmitter<string>();
@Input('mobile') set setMobileValue(value) {
this.msisdn_confirm = this.msisdn = value;
}
Renaming inputs and outputs by passing a string parameter to the decorator is discourages. Rather use
@Output() mobileChange: EventEmitter<string> = new EventEmitter<string>();
@Input() set mobile(value) {
this.msisdn_confirm = this.msisdn = value;
}