../Mobile/sql/mobile_setup/mysql4-install-0.1.0.php

<?php
$installer = $this;
$installer->startSetup();


$installer->addAttribute("customer", "mobile",  array(
    "type"     => "varchar",
    "backend"  => "",
    "label"    => "Mobile Number",
    "input"    => "text",
    "source"   => "",
    "visible"  => true,
    "required" => false,
    "default" => "",
    "frontend" => "",
    "unique"     => false,
    "note"       => ""

    ));

        $attribute   = Mage::getSingleton("eav/config")->getAttribute("customer", "mobile");


$used_in_forms=array();

$used_in_forms[]="adminhtml_customer";
$used_in_forms[]="checkout_register";
$used_in_forms[]="customer_account_create";
$used_in_forms[]="customer_account_edit";
$used_in_forms[]="adminhtml_checkout";
        $attribute->setData("used_in_forms", $used_in_forms)
        ->setData("is_used_for_customer_segment", true)
        ->setData("is_system", 0)
        ->setData("is_user_defined", 1)
        ->setData("is_visible", 1)
        ->setData("sort_order", 100)
        ;
        $attribute->save();



$installer->endSetup();