(Bloomberg) — Cable & Wireless Plc., the UK's second-biggest phone company, agreed to sell its 20 percent stake in Bahrain Telecommunications Company B.S.C. to the Persian Gulf country's government for $506.1 million.Cable & Wireless International agreed to sell the stake in the fixed line and mobile telecommunications operator to three Bahraini government entities, Berkshire, England-based Cable & Wireless said in a PR Newswire statement.