function showError(error) {
  if ($(error).style.display == 'none')
      Effect.Appear(error, { duration: 0.25});
  else
    Effect.Appear(error, { duration: 0.25, from: 0.5, to: 1.0});
}

function hideError(error) {
  Effect.Fade(error, { duration: 0.25});
}

function validateCellNumber() {
  var re = /[0-9|\+|\s|\-\(\)]*/g;
  var t = $F('user_cell_number');
  return t.replace(re, '').length != 0;
}