materio-base-d7/sites/all/modules/contrib/form/phone/phone.install

<?php

/**
 * @file
 * Install/Update/Uninstall functions for phone module
 */

/**
 * Implements hook_field_schema().
 */
function phone_field_schema($field) {
  return array(
    'columns' => array(
      'value' => array(
        'type' => 'varchar',
        'length' => 255,
        'not null' => FALSE,
      ),
    ),
  );
}


// TODO: data migration from the old DB structure, could be tough..