Para setar o campo de celular do Checkout do Woocommerce, campo Cell_Phone, pode ser utilizado a function.php do tema.
add_filter('woocommerce_billing_fields', 'conexaogt_make_phone_number_required', 10, 1 );
function conexaogt_make_phone_number_required( $address_fields ) {
$address_fields['billing_cellphone']['required'] = true;
return $address_fields;
}
