Name the call sign for ERP W of 4
CREATE TABLE table_name_20 (call_sign VARCHAR, erp_w VARCHAR)
SELECT call_sign FROM table_name_20 WHERE erp_w = 4
### Context: CREATE TABLE table_name_20 (call_sign VARCHAR, erp_w VARCHAR) ### Question: Name the call sign for ERP W of 4 ### Answer: SELECT call_sign FROM table_name_20 WHERE erp_w = 4