<form class="example-form">
  <mat-form-field class="example-full-width" appearance="fill">
    <mat-label>Telephone</mat-label>
    <span matPrefix>+1 &nbsp;</span>
    <input type="tel" matInput placeholder="555-555-1234">
    <mat-icon matSuffix>mode_edit</mat-icon>
  </mat-form-field>
</form>
