What causes international delivery failures?
When shipping outside the U.S. and U.K., carriers and customs authorities require a recipient phone number. They use it to:
Send tracking and delivery notifications
Complete customs clearance (many countries mandate a contact number on invoices)
Reach the recipient if there's an address or delivery issue
U.S. and U.K. shipments don't require a phone number, so if you're only shipping domestically within these countries, no changes are needed. But if you fulfill orders to other regions - Europe, Asia, Latin America, the Middle East, or elsewhere - a missing phone number can cause shipments to be held at customs, fail delivery, or be returned to sender.
The good news: it takes less than a minute to fix.
Shopify
Open your Shopify admin and go to Settings > Checkout
Find Shipping address phone number
Select Required
Click Save
WooCommerce
The billing phone field is required by default in WooCommerce. If your theme or a plugin has made it optional, you can restore it:
Option A — Plugin Install Checkout Field Editor and set the phone field to required.
Option B — Code snippet Add the following to your theme's functions.php:
add_filter('woocommerce_billing_fields', function($fields) { $fields['billing_phone']['required'] = true; return $fields; });Wix
Open your Wix dashboard and go to Settings > eCommerce Settings > Checkout
Find Phone number under checkout form fields
Set it to Required
Click Save
How do I know it's working?
Place a test order and confirm the phone number field appears as required at checkout.