function lengthcheck(checkobject: string; length: integer) : boolean;
begin
  if LENGTH(checkobject) <> length then lengthcheck:=true;
end;

procedure TFormMain.DBEDtelephoneExit(Sender: TObject);
begin
  if lengthcheck(DBEDtelephone.text, 11)=true then begin
    MessageDlg('Telephone number must be input correctly' +#10 +'Values must be between 0-9', mtWarning, [mbOK], 0);
    DBEDtelephone.SetFocus;
  end;
end;