Revised function to apply to multiple forms

<?php
// http://www.gravityhelp.com/forums/topic/sending-additional-information-to-authorizenet-via-namevalue-pairs#post-146608
add_filter('gform_authorizenet_before_single_payment','my_anet_custom_fields', 10, 2);
function my_anet_custom_fields($transaction, $form_data) {

        # GET DATA FROM FORM INPUT BASED ON FORM ID
        # CREATE MULTIPLE FORM to FIELD MAPPINGS HERE

        # form 75 uses input_3 for the phone number
        if (rgpost('form_id') == 75 {
                $form_data["phone"] = rgpost('input_3');
        }
        # form 14 uses input_17 for the phone number
    else if (rgpost('form_id') == 14 {
                $form_data["phone"] = rgpost('input_17');
        }

        # ADD DATA TO TRANSACTION OBJECT
        $transaction->phone = $form_data["phone"];

        return $transaction;
}