Letakkan validasi pada nomor sel dalam sudut

<div class="form-group row">
                <input type="text" class="form-control" appPhoneMask placeholder="Mobile Number" autocomplete="off"
                    [ngClass]="{ 'is-invalid': (f.inputCountryCode.errors && mobileNumberform.submitted) }"
                    formControlName="inputCountryCode">
                <div *ngIf="(f.inputCountryCode.invalid ) || (f.inputCountryCode.invalid && (f.inputCountryCode.dirty || f.inputCountryCode.touched))"
                    class="invalid-feedback">
                    <div *ngIf="f.inputCountryCode.errors.required">This field is required.</div>
                    <div *ngIf="f.inputCountryCode.errors.pattern">Invalid phone number.</div>
                </div>
            </div>
Poised Pygmy