SELECT customer_phone FROM customers UNION SELECT supplier_phone FROM suppliers
Return the phone numbers for all customers and suppliers.
[Schema (values) (types)]: | department_store |  Addresses : address_id (text) , address_details (number) | Staff : staff_id (text) , staff_gender (number) , staff_name (text) | Suppliers : supplier_id (text) , supplier_name (number) , supplier_phone (text) | Department_Store_Chain : dept_store_chain_id (text) , dept_store_chain_name (number) | Customers : customer_id (text) , payment_method_code (number) , customer_code (text) , customer_name (number) , customer_address (text) , customer_phone (text) , customer_email (number) | Products : product_id (text) , product_type_code (number) , product_name (text) , product_price (number) | Supplier_Addresses : supplier_id (text) , address_id (number) , date_from (text) , date_to (number) | Customer_Addresses : customer_id (text) , address_id (number) , date_from (text) , date_to (number) | Customer_Orders : order_id (text) , customer_id (number) , order_status_code (text) , order_date (number) | Department_Stores : dept_store_id (text) , dept_store_chain_id (number) , store_name (text) , store_address (number) , store_phone (text) , store_email (text) | Departments : department_id (text) , dept_store_id (number) , department_name (text) | Order_Items : order_item_id (text) , order_id (number) , product_id (text) | Product_Suppliers : product_id (text) , supplier_id (number) , date_supplied_from (text) , date_supplied_to (number) , total_amount_purchased (text) , total_value_purchased (text) | Staff_Department_Assignments : staff_id (text) , department_id (number) , date_assigned_from (text) , job_title_code (number) , date_assigned_to (text);